Reach Custom Game / Forge Map causes Fatal Error

Hey, wonder if anyone’s heard this before or knows how to fix it:

I started seeing crashes in my Reach Forge World map while making it. This would happen when I delete an item. But I just continued on because the crash wasn’t frequent and finished the map.

Now when I play it in Custom Game mode, it crashes me and anyone else in my game when the second round begins. Anyone see this before or know whether I can fix my map?

The specific error is a UE4-MCC Fatal Error crash.