Product and version : Filemaker Pro 16 Advanced 16.0v4
Hardware : E3 Xeon 1240v2 8 go ram
Trigger on object save must cancel save if test return false, not only for the try.
How to replicate :
Place a field on a layout. Add a trigger on object save to this field = exit script : "false".
Modifying datas => first time you try to commit record trigger work fine (save was canceled). if you trying to commit another time the same record the trigger on object save aren't performed and change to the field are saved.
Workaround (if any)
The real case is to have a trigger if $$flag then exit script "true" else exit script "false".
Trigger on object save must be be prformed each time you try to save modification on a field