I took a look at the MFA. The problem is that a Group.Obstacles shortcut in the global event editor is associated with this object. You can see 2 instances of Group.Obstacles in the global event editor, the second one is associated with the 9 Slices Object extension.
How is this possible? Did you rename a 9 Slices Object object to Group.Obstacles at some point? O_o
Anyway, to fix it, use Edit / Find Object on Group.Obstacles in the Global Event editor to find the first Group.Obstacles object and then press F3 to find the second one. Select this second object, you'll see there is a Is Overlapping condition associated with this object. Delete this action, this will remove the reference to the object.