Fun times!
- Assignment operators were being treated wrong because "self" is now no longer an instance ID and so it would fall through the normal checks for what to do, assigning the right-hand value only because it was still on the stack. There might be more of the kind.
- Global variables were inaccessible because only half of my bug was fixed,
https://bugs.yoyogames.com/view.php?id=30287
https://help.yoyogames.com/hc/en-us/community/posts/360012721257--BUG-variable-struct-get-returns-true-for-built-in-globals
I have uploaded a new build (1.0.25a) to address these.