Partial Master on Marks not working

I cannot put partial masters to work with marks. I have created a regular version for the cedila but it doesn’t work. See attachement.

I am doing fine with partial masters on the letters and numbers, so I know the process is correct.

The cedila alone is well interpolated, but not in a component glyph like Ç.

How can I solve this?


The preview of compound glyphs is not reliable in this respect; I recommend you test with the Adobe Fonts folder: