Make Component Glyph vs. Glyphdata.xml

Apparently “Make Component Glyph” and “Generate Glyphs” doesn’t work well for glyphs variants like adieresis.ss01 when I use my own GlyphData.xml.
I have a.ss01, dieresiscomb and my own GlyphData.xml (without any reference to the above named, just for some symbols).

I tried Cmd+Shift+G > “adieresis.ss01”. But the new glyph remains empty. I hit Cmd+Shift+Alt+C, but the glyph remains empty.

After renaming the GlyphData.xml everything works fine. A glyphData file with just header but no entries is also OK.

Do you have the GlyphData next to the file or in the Info folder?

Next to the file or one stage up.

Wait, I have it at both places! And they look identical … I’ll check that.

Deactivating the GlyphData in the info folder by renaming and restarting doesn’t help.

can you send me your files?