Another empty base glyph confusion

I’m working on a COLR-font and the a-acute looks fine in its regular form, but the moment I start working with the COLR-layers I get an “empty base glyph” in the middle of it.

I tried removing all component glyphs as it consisted of the A- and acutecomb-components, nothing seems to remove the warning.

nevermind, found it in one of the layers.