I think I maybe solved the issue? I mean, its def a workaround lol but it can help MacOS users in the meantime -- original post on Naocat's thread regarding a similar issue on Mac RE: avatar not loading.
This method bypasses the need to press ESC (which throws that -50 error) and allows MacOS users to directly upload their asset folder to the corresponding AppData folder the program defaults to using. GLHF!
Viewing post in Can't navigate to the usr folder
Found the page on the Wayback Machine!
https://web.archive.org/web/20240830232344//t/3426276/mac-doesnt-...
Not totally enlightening, but maybe it'll help.