Import it with openbrf and replace it in human_mounted so you can better analyze the problem if you dont mind since im also having trouble taking screenshots in M&B (they dont get uploaded by steam for some reason).
I've noticed the vanilla one has 248 frames while this has 247 could that be an issue?
EDIT: Nevermind, it's working now, i tried it yesterday and it had some problems, sorry for wasting your time