Submix Settings on Submix Send Settings cannot be updated at runtime in SubmixSendVolumeComponent

Source: UDN ticket

Stepping through, when SetSubmixSendSettings() is called on the SubmixSendVolumeComponent, the SubmixSendSettings on the Component initially get changed before the NotifyDataChange() is called.

However, when the FProxyMutator_SubmixSend::Apply() runs, the SubmixSendSettings have not updated and will revert back to whatever was set initially (manually in the editor on the component itself)

Workaround to exit the volume and re-enter after calling ::SetSubmixSendSettings on the volume component does not seem to work either. 

1) Create base AVolume or AActor class

2) Create and add USubmixSendVolumeComponent to it, the send option set to Manual in this case.

3) In tick create new TArray<FAudioVolumeSubmixSendSettings> with new SendLevel, MinSendLevel, MaxSendLevel, MinSendDistance, MaxSendDistance, call SetSubmixSendSettings(NewSettings). Or just try and call SetSubmixSendSettings() once the game is running somewhere.

4) Observe in the SubmixSendVolumeComponent the new settings are set in SetSubmixSendSettings(), but have not persisted/updated when Apply() is called