I was wrecking head on this during Christmas day, not the best thing to do
As I was making specimens in Adobe Illustrator, I found a change in the character selection box. I thought this had to do with the components I used or some faulty metric, so I brute-forced the various metrics through custom parameters. After this I stripped the font until I only had a solid version, and even the lower case ‘d’ left, but the problem remained.
I revisited some older exports, and these didn’t have this problem. Upon re-exporting the older source files, the same selection fault appeared.
The fonts have a higher UPM (3072) and are all based on the same metrics. I have only been working on newer designs and thought the selection bug was something which I still had to fix, so can’t say from what update this started.
I’ve tried to replicate the issue the past month but haven’t gotten much closer, as previous exports still work fine. Even without color layers the problem remains.
Yes: This could be an Adobe issue, as I don’t have this problem in textedit/pages or other editors. (it does remain in Photoshop and other Adobe programs). But why do older exports work correctly and new versions don’t?
I’ve compared the tables, the source Glyphs file is exactly the same, just the version of G3 used to export is different.
There are differences in the hhea linegap (set to a certain value in the new export, zero in the old one) and most important a negative sxHeight and sCapHeight. When correcting and compiling back it all works fine.
Of course I can fix it this way, but it’s a bit of a workaround.