I don't really have a very good way to describe this bug because it's so weird. It requires three specific things to happen in order to trigger the bug, and I don't know which of the things is the cause of it. I'll do my best to explain, though...
What is happening:
These three things are conspiring together to trigger an action when they shouldn't...
1.) A boolean state (such as "Is visible" or "Is falling")
2.) A sub-event with the following:
3.) Two "Overlapping at offset" conditions separated by an OR
How to recreate:
Open and run the attached .cap and follow the instructions.
More description:
You need a boolean condition like "Is visible" or "Is falling." It doesn't seem to work with other kinds of conditions where you compare a ranged value (such as Opacity or Angle).
Then you need a sub-event under that condition, with TWO "Overlapping at offset" conditions separated by an OR. If you have just one "overlapping at offset" condition the bug won't trigger. If you use a regular overlap it won't trigger. If you use a single event with no sub-event it won't trigger.
I've tested this thing eight ways to Sunday and I don't know which individual part is triggering the bug. As near as I can tell, it's all three together somehow. Anyway, it's weird.
The Magical Boolean/Offset/OR/Unicorn Bug example