The metric seems to be broken when editing a glyph containing .full in the name suffix. These suffixes: .full.below or .below.full or just .full are the same.
Broken metric lines
Normal metrics with alignment zone and metric lines
The suffix “.full” is used for CJK font. It is used for full width, none ideographic glyphs. I’m afraid you need to change the suffix.
I see. I didn’t know that.
Thanks, Georg.