A font I’m working on in Glyphs 3 autogenerates the language system:
languagesystem latn NLD;
and the substitution rules for jacute and Jacute
The same Glyphs file when opened in Glyphs 4 has the same language support and sub rules initially but if I click ‘Update’ it then removes the ‘languagesystem latn NLD;’ and the sub rules for jacute and Jacute.
I can add them back in manually but I’m guessing this is unintended.