We recently encountered an odd issue where loading into our main world partitioned map would result in a crash caused by all streaming cells getting loaded at the same time. Turns out this was caused by mistakenly async loading our map asset via a streaming manager request before traveling to it. During async loading of the map asset, UWorldPartition::IsServerStreamingEnabled gets invoked via UWorldPartitionLevelStreamingDynamic::PostLoad and since the owning world type is set to inactive at that moment, the value that gets cached for bCachedIsServerStreamingEnabled is false. When we later travel to the map, since streaming is disabled, all cells get loaded.
We fixed the issue by making sure no map asset is getting loaded via the streaming manager, but should that be supported? Should bCachedIsServerStreamingEnabled be reset when the owning world type changes?
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-264770 in the post.