Correction: The desktop wallpaper is OK for the regular ID & PW login screen. It is just at this new FV ID&PW login that it isn't there.

OK this has just gotten stranger.  I updated Jamf Connect on my intel MBP and the FileVault icons are there. But they are missing on my M1 MBP.  To clarify: I don't mean that the specific pictures are missing and replaced with generic icons.... I mean the entire login screen is no longer icons to click on, it is now an ID box and a Password box.

Hey @AVmcclint I believe that is an arm Processor thing. Arm Processor has the username and password field for FileVault: https://derflounder.wordpress.com/2021/01/17/filevault-login-screen-differences-between-intel-and-apple-silicon-macs/

On the M1 system can you try running this command in terminal if you can get logged in to an admin account:

sudo diskutil apfs updatePreboot /

Then reboot and check if accounts show. This should update changed passwords in the system. 

You can also use these commands to check if filevault/secure token is still enabled for users. 

sudo fdesetup list

sysadminctl -secureTokenStatus username

I ran those commands and everything looks fine as far as tokens and such, but it still only gives the ID & PW login.  @gabe2385 thanks for the info on the difference between Apple Silicon and intel with regard to this, but it still doesn't explain why the login screen changed when all I did was update Jamf Connect from 2.12 to 2.18.  Everything still works, but this is a major change to the user experience that I need to either switch back to the icon FV login or have a **bleep** good explanation ready for my bosses who will wanna know why it changed only on some computers but not all. 

Try pressing Option+Enter, this switches between User List Icons and Name/Pass-boxes on Apple Silicon running macOS 12+.

Another option is to get for macOS configuration profile that sets the login window type as List or Name/Pass. This also affects the FV boot screen on Apple Silicon.