I worked the issue out now. The user-assigned managed identity was associated with the elastic job agent, although no jobs had been setup to use it yet (all jobs for the target server/DB’s where still using DB users mapped from logins). All databases that existed prior to associating the user-assigned managed identity to the elastic agent server where unaffected, but jobs for databases created after this point would fail with the “The server principal "ac1971e9-381b-449b-9e1a-9cc276fc2985@b5313c9d-fb0d-47af-bc87-7c050bffbdc3" is not able to access the database”. Un-associating the user-assigned managed identity from the elastic agent server resolved the problem.