I have posted this already in Feedback Assistant back in September with detailed steps to reproduce and have not heard back. Posting a brief overview here in hopes that Apple acknowledges and addresses this issue that is still present in recent Sonoma betas. This is preventing our organization from updating to Sonoma, however the Apple maximum update deferral timeline of 90 days is running out at Christmas.
The Switch User option is missing from the Lock Screen on macOS Sonoma if only one person has ever signed in for an enterprise device with an MDM pushed (and verified) configuration profile which allows user switching and network users to sign in to the device. It only shows users who are not hidden and have a home folder. This locks out all users without a hard reboot if nobody else exists on the device, or the user can do something that is very unintuitive if there are 2 or more users who have signed in. They can click any other user than the one who was logged in when the lockscreen process started, and that will let them erase the username of the user they clicked and log in themselves.
What is missing is "Other..." or "Switch User", which were on the Lock Screen for pervious versions of macOS. The login screen works just fine, it's the lock screen that's now ignoring configuration profiles or just doesn't have the same settings as the loginwindow process.
