OnlineServices-Lobbies: Crash when host migration message is received and the next host has already left the session

A crash occurs at FindChecked in the code below.

	if (PreparedServiceChanges->OwnerAccountId)
	{
		InternalPublicData->OwnerAccountId = *PreparedServiceChanges->OwnerAccountId;

		if (bDispatchNotifications)
		{
			Params.LobbyEvents->OnLobbyLeaderChanged.Broadcast(FLobbyLeaderChanged{ InternalPublicData, MemberDataStorage.FindChecked(InternalPublicData->OwnerAccountId) });  //<<<<<<<
		}
	}

1. Prepare the project using OnlineServicesEOS
2. launch 3 game processes
3. Log in to EOS on all clients
4. execute CreateLobby on client A
5. execute FindLobbies on clients B/C and join the lobby
6. when there are 3 members in the lobby, have A and B leave from the lobby at the same time
7. repeat step 4~6

Result:

Crash occurs in client C

See call stack and [Link Removed]

KERNELBASE.dll!00007ffe909eba99()    Unknown
UnrealEditor-Core.dll!ReportAssert(const wchar_t * ErrorMessage, void * ProgramCounter) Line 1828    C++
UnrealEditor-Core.dll!FWindowsErrorOutputDevice::Serialize(const wchar_t * Msg, ELogVerbosity::Type Verbosity, const FName & Category) Line 84    C++
UnrealEditor-Core.dll!FOutputDevice::LogfImpl(const wchar_t * Fmt, ...) Line 70    C++
[Inline Frame] UnrealEditor-Core.dll!FOutputDevice::Logf(const wchar_t[49] &) Line 249    C++
UnrealEditor-Core.dll!AssertFailedImplV(const char * Expr, const char * File, int Line, void * ProgramCounter, const wchar_t * Format, char * Args) Line 148    C++
UnrealEditor-Core.dll!FDebug::CheckVerifyFailedImpl2(const char * Expr, const char * File, int Line, const wchar_t * Format, ...) Line 649    C++
[Inline Frame] UnrealEditor-OnlineServicesCommon.dll!TMapBase<UE::Online::TOnlineId<UE::Online::OnlineIdHandleTags::FAccount>,TSharedRef<UE::Online::FLobbyMemberInternal,1>,FDefaultSetAllocator,TDefaultMapHashableKeyFuncs<UE::Online::TOnlineId<UE::Online::OnlineIdHandleTags::FAccount>,TSharedRef<UE::Online::FLobbyMemberInternal,1>,0>>::FindChecked(const UE::Online::TOnlineId<UE::Online::OnlineIdHandleTags::FAccount> & Key) Line 672    C++
UnrealEditor-OnlineServicesCommon.dll!UE::Online::FLobbyClientData::CommitServiceSnapshot(UE::Online::FLobbyClientDataCommitServiceSnapshot::Params && Params) Line 247    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::FLobbiesEOSGS::ProcessLobbyNotificationImplOp::__l2::<lambda_3>::operator()(UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl> & InAsyncOp) Line 2110    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::Private::TStep<void>::SetExecFunction::__l2::<lambda_1>::operator()() Line 500    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep::__l8::<lambda_1>::operator()() Line 1031    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::Execute<`UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep'::`8'::<lambda_1>>(UE::Online::FOnlineAsyncExecutionPolicy ExecutionPolicy, UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep::__l8::<lambda_1> && Callable) Line 1075    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep() Line 1025    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::Private::TStep<void>::SetExecFunction::__l2::<lambda_1>::operator()() Line 471    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep::__l8::<lambda_1>::operator()() Line 1031    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::Execute<`UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep'::`8'::<lambda_1>>(UE::Online::FOnlineAsyncExecutionPolicy ExecutionPolicy, UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep::__l8::<lambda_1> && Callable) Line 1075    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep() Line 1025    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::Private::TStep<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::SetExecFunction::_l2::<lambda_1>:[Image Removed])::_l6::<lambda_2>::operator()(const UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot> & Value) Line 393    C++
[Inline Frame] UnrealEditor-OnlineServicesEOSGS.dll!TFutureBase<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::Next::__l2::<lambda_1>::operator()(TFuture<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>) Line 1318    C++
[Inline Frame] UnrealEditor-OnlineServicesEOSGS.dll!FutureDetail::SetPromiseValue(TPromise<void> &) Line 1285    C++
UnrealEditor-OnlineServicesEOSGS.dll!TFutureBase<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::Then::__l2::<lambda_1>::operator()() Line 1302    C++
[Inline Frame] UnrealEditor-OnlineServicesEOSGS.dll!Invoke(TFutureBase<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::Then::__l2::<lambda_1> &) Line 47    C++
[Inline Frame] UnrealEditor-OnlineServicesEOSGS.dll!UE::Core::Private::Function::TFunctionRefCaller<`TFutureBase<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::Then<`TFutureBase<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::Next<``UE::Online::Private::TStep<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::SetExecFunction<UE::Online::FLobbiesProcessLobbyNotificationImpl,`UE::Online::FLobbiesEOSGS::ProcessLobbyNotificationImplOp'::`2'::<lambda_1>>'::`2'::<lambda_1>::operator()'::`6'::<lambda_2>>'::`2'::<lambda_1>>'::`2'::<lambda_1>,void __cdecl(void)>::Call(void *) Line 405    C++
[Inline Frame] UnrealEditor-OnlineServicesEOSGS.dll!UE::Core::Private::Function::TFunctionRefBase<UE::Core::Private::Function::TFunctionStorage<1>,void __cdecl(void)>::operator()() Line 555    C++
[Inline Frame] UnrealEditor-OnlineServicesEOSGS.dll!FFutureState::SetContinuation(TUniqueFunction<void __cdecl(void)> &&) Line 95    C++
UnrealEditor-OnlineServicesEOSGS.dll!TFutureBase<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::Then<`TFutureBase<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::Next<``UE::Online::Private::TStep<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::SetExecFunction<UE::Online::FLobbiesProcessLobbyNotificationImpl,`UE::Online::FLobbiesEOSGS::ProcessLobbyNotificationImplOp'::`2'::<lambda_1>>'::`2'::<lambda_1>::operator()'::`6'::<lambda_2>>'::`2'::<lambda_1>>(TFutureBase<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::Next::__l2::<lambda_1> Continuation) Line 1307    C++
[Inline Frame] UnrealEditor-OnlineServicesEOSGS.dll!TFutureBase<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::Next(UE::Online::Private::TStep<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::SetExecFunction::_l2::<lambda_1>:[Image Removed])::_l6::<lambda_2>) Line 1316    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::Private::TStep<UE::Online::TDefaultErrorResultInternal<UE::Online::FLobbyServiceSnapshot>>::SetExecFunction::__l2::<lambda_1>::operator()() Line 386    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep::__l8::<lambda_1>::operator()() Line 1031    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::Execute<`UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep'::`8'::<lambda_1>>(UE::Online::FOnlineAsyncExecutionPolicy ExecutionPolicy, UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep::__l8::<lambda_1> && Callable) Line 1075    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::ExecuteNextStep() Line 1025    C++
[Inline Frame] UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::TOnlineAsyncOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::Start() Line 1014    C++
UnrealEditor-OnlineServicesEOSGS.dll!UE::Online::FOnlineAsyncOpQueue::TWrappedOp<UE::Online::FLobbiesProcessLobbyNotificationImpl>::Start() Line 70    C++
UnrealEditor-OnlineServicesCommon.dll!UE::Online::FOnlineAsyncOpQueueParallel::Tick(float DeltaSeconds) Line 127    C++
UnrealEditor-OnlineServicesCommon.dll!UE::Online::FOnlineServicesCommon::Tick(float DeltaSeconds) Line 178    C++
[Inline Frame] UnrealEditor-Core.dll!Invoke(bool(FTSTickerObjectBase::*)(float)) Line 66    C++
[Inline Frame] UnrealEditor-Core.dll!UE::Core::Private::Tuple::TTupleBase<TIntegerSequence<unsigned int>>::ApplyAfter(bool(FTSTickerObjectBase::*)(float) &) Line 309    C++
UnrealEditor-Core.dll!TBaseRawMethodDelegateInstance<0,FTSTickerObjectBase,bool __cdecl(float),FDefaultDelegateUserPolicy>::Execute(float <Params_0>) Line 518    C++
[Inline Frame] UnrealEditor-Core.dll!TDelegate<bool __cdecl(float),FDefaultDelegateUserPolicy>::Execute(float) Line 549    C++
UnrealEditor-Core.dll!FTSTicker::FElement::Fire(float DeltaTime) Line 157    C++
UnrealEditor-Core.dll!FTSTicker::Tick(float DeltaTime) Line 110    C++
UnrealEditor.exe!FEngineLoop::Tick() Line 6162    C++
[Inline Frame] UnrealEditor.exe!EngineTick() Line 61    C++
UnrealEditor.exe!GuardedMain(const wchar_t * CmdLine) Line 180    C++
UnrealEditor.exe!GuardedMainWrapper(const wchar_t * CmdLine) Line 118    C++
UnrealEditor.exe!LaunchWindowsStartup(HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, char * __formal, int nCmdShow, const wchar_t * CmdLine) Line 258    C++
UnrealEditor.exe!WinMain(HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, char * pCmdLine, int nCmdShow) Line 298    C++
[Inline Frame] UnrealEditor.exe!invoke_main() Line 102    C++
UnrealEditor.exe!__scrt_common_main_seh() Line 288    C++
kernel32.dll!BaseThreadInitThunk()    Unknown
ntdll.dll!00007ffe92fdcc91()    Unknown