Sean,
Unfortunately, it doesn’t seem like there’s a back-up. I created a new semi-functional replacement to continue development so I guess it’s probably more efficient to give up on recovery of the old behavior tree. It’s not going to be easy to reproduce as it seems to be a rare occurance (the access violation bug itself as well). I’ll be starting a back-up regime as a counter measure. If it does occur again, I’ll submit file histories to see if we can pin-point the problem that occurred.
Thanks.