It seems there’s no CustomFilter.plist anymore? And almost all of my smart and list filters are missing in G3?
Glyphs 3 has its own app support folder and settings are not migrated. This allows using of Glyphs 2 and 3 side by side.
So you need to rebuild your filters. You might be able to manually copy the file from the Glyphs 2 to the Glyphs 3 folder.
Ah of course that makes sense, I copied the file in and it loaded!