Shadowbonnie7 is having the same issue while making a behavior.
The Y value is null. I haven’t heard an update. I suggested it could be a variable or division by zero. I know the new variable syntax or autocomplete has issues. It doesn’t seem as forgiving when dealing with undeclared variables or non-existent objects. I’m not saying your issue is related to that but it could be connected.
I submitted a report on crashes when using a child name that doesn’t exist. It seems to be tied to arrays but IDK. Either way, they verified it and are fixing that bug.