Changing ISM/HISM collision response at runtime does not update the collision properly.
Found in 4.20 CL# 4369336, 4.21 CL# 4753647, 4.22 CL# 6063286, 4.23 CL#6368684
The collision change properly works for the normal static mesh. Once the pawn ends overlap with the mesh by moving out of it, it is blocked from walking inside the mesh again. The collision change does not work for ISM/HISM. The EndOverlap event triggers as soon as the pawn starts overlapping with an instance, sets the collision response to block, but the pawn can still move through the mesh.
The EndOverlap event triggers only when the pawn actually leaves the collision area of the mesh instance and once the pawn tries to re-enter any mesh of the ISM/HISM it is blocked from doing so. The GetOverlappingActors function should properly return all overlapping actors.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-74340 in the post.