Trying to open the settings in Rhino 5 for Mac 5.5.5 (5F96) crashes the software instantly. This happens every time, regardless of using the shortcut or the dropdown menu, on new and existing files. As far as I can tell, this only happens since the Big Sur Update.
Is this a known problem and if so, are bugs still fixed for R5?
Yes, it’s known and it won’t be the only issue on macOS 11. We had to add Big Sur as unsupported for Rhino 5 for Mac. Rhino - Rhino 5 System Requirements You’ll have to roll back to an earlier macOS or alternatively try Rhino 7.