Check if a settlement at the roman turn is rebelling (use "toggle_fow" in the console)

Mostly it is due to that.

You can use "add_population -4000 NAMEOFCITY" to minimize the chance of a reballion or take it by FD for one turn.

You got the fixes for 1.2? Any minimods?
Try to move a unit just one space and save and press turn, sometimes it helps.

Also de-activating the script for one turn might help.

XSamatan