Access Violation on NavMesh generation for Random Generated Level, please send help

We’re trying to build a random level and refresh/generate navmesh at runtime, get this crash intermittently but don’t know what’s causing it. If anyone can chime in with any tips that would be great.

Access violation - code c0000005 (first/second chance not available)

SomeGame_Win64_Shipping!rcMarkWalkableTrianglesCos()
SomeGame_Win64_Shipping!UAnimBlueprintGeneratedClass::PurgeClass()
SomeGame_Win64_Shipping!FRecastTileGenerator::GenerateCompressedLayers()
SomeGame_Win64_Shipping!FRecastTileGenerator::GenerateTile()
SomeGame_Win64_Shipping!FRecastTileGenerator::DoWork()
SomeGame_Win64_Shipping!FAsyncTask::Abandon()
SomeGame_Win64_Shipping!FQueuedThread::Run()
SomeGame_Win64_Shipping!FRunnableThreadWin::Run()

We’re getting this as well. Seems like there’s no way to solve this. If you have any solution please post here I will follow.

The only thing we could think of was updating to UE 4.20, since the patch notes have made mention of bug fixes that sound similar to this.

So far we haven’t encountered it since updating.