In my font, I have a number of Private Use glyphs, plus a number of non-exporting “other” glyphs.
Using Glyphs Mini 2.1.3 (99), from the main Font view, if I double-click on a private-use glyph, this opens the editor window as normal. However, if I double-click on a glyph in the “other” section, neither the glyph itself nor any of the global guidelines are visible, and the glyph name does not appear at the top of the tab.
I have an older version of the font, in which this problem is not happening. The difference between the older version and the newer version is the addition of about 1500 glyphs.
Is this a bug in Glyphs Mini, or a limitation on the number of allowable glyphs? I did not see a maximum number of supported glyphs in the documentation handbook or on the website.
Glyphs files:
http://carolingianrealm.blog/glyphs/Carogine-Italic.zip
This is running on MacOS Mojave, 10.14.6.