It's tough to be sure, but it could be a jump to relocated data the event is not agreeing with, in order for it to end correctly. This would happen to me back on some events and I wound up just moving the whole thing from where I jumped, so there was no returning back. I'm not sure exactly what causes it sometimes, it's not like every event needs to be moved like this, but it seems sometimes maybe under certain circumstances it doesn't like to jump back and forth, resulting in this issue.
Besides this, you could try jumping back with another subroutine jump instead of returning with FE, or visa versa. Sometimes this will work.
Besides this, you could try jumping back with another subroutine jump instead of returning with FE, or visa versa. Sometimes this will work.