City Revolt - questions and CTDs

[Makanyane]

With your save if I leave all or most of garrison in I CTD, if I remove most and leave 1 or 2 troops it seems to revolt OK, 3 or more left in and CTD comes back. I was previously testing with only 1 unit (didn't occur to me that number could make difference, LOL)

Note: I've only tried two/three instances of each so far, will keep trying to check consistency of effect and try same on my save.
EDIT: looks same on my save adding one more unit OK, adding two = 3 garrison =CTD, unfortunately this does disprove my hope / belief that this wasn't going to happen on AI turns due to presence of garrison.