BE 20.3.1188 RALUS backups started failing, edit job says Failure to browse [ROOT]

Backups were working for a long time then suddenly started failing with job log
V-79-57344-33967 - Directory not found. Cannot backup directory / and its subdirectories.
Final error: 0xe00084af - The directory or file was not found, or could not be accessed.

Attempt to edit job result in a popup titled "Browse failure" and contents "Failure to browse [ROOT]"

Establish trust succeeds

Test credentials: server's login = success. [ROOT] = Test Failed. No option to change or edit credentials.

I am desperate. Anything I find online is years out of date or not the exact error I am experiencing.