Hey, digging into this a bit since we are having the same problem.
Log:
LogGPULightmass: GPULightmass is now running at full speed
LogGPULightmass: Resizing GPULightmass scratch tile pool to (12, 12) 816x816
LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
LogGPULightmass: Cached ray tracing scene is invalidated due to material changes
[579]LogWindows: Error: appError called: Assertion failed: ResourceMap.Contains(Resource) [File:D:\build\++UE5\Sync\Engine\Source\Runtime\RenderCore\Private\RenderGraphValidation.cpp] [Line: 790]
Resource at 000007097BB4FC00 registered with pass LightmapGBufferTile is not part of the graph and is likely a dangling pointer or garbage value.
This seems to be the trigger, not sure what material changes could be happening in the scene, will try to find what material/s are causing this.
LogGPULightmass: Cached ray tracing scene is invalidated due to material changes