Hi.
It seems that FBox constructed by MakeBox in blueprint have a IsValid Flag to false.
I had the problem in a HierachicalInstancedStaticMesh in the GetInstancesOverlappingBox function as it check the validity of the box before transforming it and always return empty Array with this box.
I had created a BluePrintFunction MakeValidBox to replace the usual one and it works correctly now.
However i cannot provide a patch because i didn’t find where the MakeBox function is exposed to blueprint.
Cheers