I installed the latest version of Glyphs and it completely confused the arrangement of glyphs in the general view.
Is there any way to restore the old layout, where glyphs were ordered by class (capitals, lowercase, numbers etc.)?
This font was opened from a font file and has a stored glyph order (that why it says “Predefined Sorting”). You find this in Font Info > Font > Custom Parameters > Glyph Order. Delete this entry and you are back to normal.
Solved, thanks !