UE4 AkOcclusionObstructionService Crash

Question

We are using Wwise 2017.2.3.6575 and UE4.19.0. 

• AkOcclusionObstructionService::CalculateObstructionOcclusionValues doesn't guarantee thread safety when doing its line traces.
• When CurrentWorld->LineTraceSingleByChannel returns a hit actor that is a landscape with foliage, there's the potential that the async task for updating foliage instanced mesh components can happen at the same time as the call to OutHit.Actor->GetComponentsBoundingBox().
• This causes a crash that is hard to give a specific reproduction map for due to the specific timing problems that can occur around this.
• It's assumed that this can happen with other things return as the hit actor, but Landscape having frequent async updates, as well as having 60+ components in a normal situation make this a lot more common of an actor to crash against.
• This is occurring for us on plugin version 2017.2.3.6575.917, but the changes for plugin version 2017.2.4.6590.933 don't appear to have addressed this at all.

Answer 1

It seems changing line 167 of file AkOcclusionObstructionServer.cpp to 

CalculateObstructionOcclusionValues(in_Listeners, SourcePosition, Actor, RoomID, in_collisionChannel);

 can fix this issue temporarily.