LANG=en_US.UTF-8 Operating system: Debian 11 x86_64 It is neither possible to save documents with UTF-8 characters in their file name, nor to load them. Error messages: SAVING: Error saving the document Untitled 1: Object not accessible. The object cannot be accessed due to insufficient user rights. LOADING: The operation on ä.txt was started with an invalid parameter.
There's a lot of discussion about what happens when LANG=C in Bug 125995. This may be a related issue.