When I do any modification and then save the file, it carsh.
version:3.1.1 (3148)
MacOS:12.6
Do you get an error message after the crash?
Perhaps this is just the case with this one file. If so, can you send us the Glyphs file to or as a private message here on the forum so we can inspect it?
Any reason why you’re not using the latest version?