Further googling gets me lots of very technical pages involving writing code. This I’d rather not do, because I have no idea what I’m doing. This issue originally raised it’s head a week or so ago when a new plug-in/script behaved strangely, not showing the correct interface. (“Erode” - other people with same issue I had here: Erode Plugin doesn’t work ) This sounds like a Vanilla problem. This is before the iCloud change. So: Something is wrong either with that plug-in that has affected Glyphs across the board, or some other non-Glyphs thing has changed permissions, meaning Vanilla can’t install. I have never changed any permissions on any folder. Any help very welcome, as I’ve lost two days on this and deadline is looming…! Thanks in desperation.