Using Fusion 2.5+ 292.14, Steam running on Windows (exported to Mac application zip)
If I check "on" a flag of an object in the object's properties window (rather than turn it on in the events), the Mac version of my game doesn't seem to think the flag is on. The windows version does, however.
Attached is a simple MFA demonstrating the issue.
I have some copies of an object that belong to a qualifier. I set flag 0 "on" in the properties window of the object. The events check if flag 0 is "on" for objects of that qualifier, and if so, make the qualifier objects invisible. On Mac, they remain visible anyway, as though flag 0 was "off." But on Windows they are made invisible as expected.
If you remove the checking of the flag condition from the event, it will work - the objects will be made invisible. They will also be made invisible if you have an event to turn on flag 0 first, before checking if the flag is on. So it seems to have to do with the flag being set on outside of events.
(These events are global events by the way, but the same issue happens if they are in the regular frame events.)
For context, I've been working for a while now on a little adventure game engine that works great on Windows, and I did everything I could while working on it to keep it cross platform (really want it compatible on Mac). I had my brother test it recently on his Mac, and he sent me a video of what he saw - which was total insanity. Objects that should be hidden were visible, the player was moving only one axis at a time (and very slowly), and there was a weird black box on the side of all my dialogue windows. I don't even know where to start with some of those issues, but the objects not being made invisible was the least expected. Why should that be any different on a Mac?!