I did not removed anything. The create at start was still present but was ignored. I had to add the object in the frame again and create a new "create at start" event.
So it ended with 2 "create at start" events for the same object to fix the issue (after replacing the bad object reference). Then i could delete one of the two "create at start" event...
It was a really weird issue.
But as i said above, the "don't create at start" doesn't work when you use a frame to create your level with all the objects, and another with the game engine. Because if you let the object in the game engine frame, even with "don't create at start" they will be created because in the level frame the object is created.
One solution is to give the objects in the parent frame a unique instance value (eg 999). Then in the child frame, do:
-on start of frame, if instance value =999, destroy object.
You can use a qualifier of course, so you can destroy all the objects you need to with just one event.
(like in this example), and not having quotation marks when dealing with strings would make it at odds with all the other times the expression editor is used. I'll often have the name of a fastloop stored as an alterable string for objects, that way I can use the same code that starts the loop for a qualifier
I didn't like the new visual. This grey skin is strange
About the include frame feature, it'd be nice if Fusion imported the objects of the parent frame into the child frame's event editor like this:
Currently if I want to add events to the child frame which reference an object in the parent frame, I have to create the event in the parent frame first, then copy it to the child frame, which will import that object into the event editor. It'd be nice if Fusion imported all of those objects automatically, or at least have a button to import objects like in global events and behaviors.