Are you developing in C++, or blueprint only?
Are you using any non-standard plug-ins?
Which version of the engine are you using?
It kind of looks like you’re running a custom build of the engine; if that’s so, then it’s very likely that your code/changes have a bug, where they make some object invalid/deleted before the engine is done with it.
To know exactly which object, you’d need to examine the pointer values and the heap around that pointer, as well as where the reference is coming from (some per-instance render data) to figure out what it is.
If this happens without custom plugins in a blueprint project, using stock 5.0.3, then that’s an engine bug.
You might want to file a bug report to raise the visibility of it. I assume you’re already sending the “report this crash” error reports?
Perhaps this can help, we “solved” the issue by disabling raytracing for InstancedStaticMesh by adding r.RayTracing.Geometry.InstancedStaticMeshes=False to DefaultEngine.ini. Completely disabling raytracing also work.
Of course this is a workaround, the issue is still there, but at least we can avoid crashes until Epic releases an actual fix.