Sadly, all I can add here is a “me too”. I posted a similar question to
https://swi-prolog.discourse.group/t/problems-saving-swish-notes/1171
I find this is an intermitent problem. Sometimes I start a new notebook and saving updates works fine, othertimes I get the Permission denied. Please try a different name blues.
I also use my Google account to log in, so not sure if that’s related.