Hey 3HMonkey,
After looking into your issue, I believe it is a known problem with Preview 5 caused by an interaction between Skeletal Meshes and AnimBlueprints called to/from a UMG Widget. If you remove that call in the widget, then convert a copy from Preview 4 to Preview 5, the crash shouldn’t reappear.
Let me know if that fixes your problem.
Thanks,
Jonathan