Local Interpolation (custom parameter) appears to not work correctly?

Attached is a screen shot of a test implementation of the “Local Interpolation” custom parameter. Instances 2-9 from the left are supposed to look like the instance 8 from the right (just as a test), but instead the local Interpolation has an odd result. The “include: a, b, c, d” part of the local interpolation works as expected. Export has the same result, so it is not a display issue. Also attached is the test file (used just for testing purposes). Please review, thanks.

Test Local Interpolation.glyphs (185.8 KB)

I’m pretty sure you need to include the piece glyphs in the parameter.

I’m not sure what you mean by “piece glyphs”?

I’m not sure what you mean by “piece glyphs”? The parameter entry is per the handbook = “3; 6; 24; 24; include: a, b, c, d”

Ok, sorry, I didn’t at first understand what “piece glyphs” referred to. But, yes when I added the components that are used inside the glyphs to the local parameter include list, “include: a, b, c, d, etc.”, then as you have said, the abcd local appearance changed properly. But now all the other glyphs that use the same “piece glyphs” components don’t display properly. In the included test example those are d,g,h,o, which use some of the same “piece glyphs” components as a,b,c,d. Interestingly, the test setup which I use, has an additional nested component that is one nest deeper, and the local interpolation seems to work without including the nested component? Is that correct? Who is it necessary to include the first level nested components, when everything seems to work properly for me when not including the second level nested components. So, I will have to think of how that might work or not work given the current setup. My first reaction is that it doesn’t work, as many letters share the same components, so either the local interpolation of the included glyphs doesn’t work or the instance interpolation of the not included glyphs doesn’t work. I wonder if there is a work around that would temporarily decompose the glyph for the purpose of local interpolation without actually decomposing the glyph components for future use? I will try some things. Thanks for the quick response, which has got me thinking.