Thank you. I read this, but following another instruction after removing lowercase glyphs I do this:
Glyph > Add Glyphs>A=a B=b C=c D=d E…
and:
Glyph > Add Glyphs>Aacute=aacute Abreve=abreve Acircumflex=acircumflex Adieresis=adieresis…
You would still not need that feature. If it is all caps, you don’t need to substitute the (non-existing) lowercase shape for its uppercase counterpart. Delete the feature, recompile, and you should be good.