This is a 2-Master font
Master 1: Regular
Master 2: Shadow
When applying “Fix zero Handles” to Master 2, the path in Master 1 gets distorted.
The cause may be:
2 nodes in Master 2 are just 1 point seperated and do have handles (which are exactly on top of the nodes). After fixing this by deleting one of the close node or its handle, “Fix zero Handles” works.