Strange Culling Issue

Just upgraded to 4.19.2 and my HISM with one specific material is being culled in what seems to be a random fashion. Even setting endculldistance doesn’t seem to fix the issue. Does anyone have any ideas what would cause HISM to selectively cull instances based on material properties?

This issue did not occur in 4.15 or 4.16.

Thanks for your help.