screenUnlockMode = 2 default of loginwindow makes it impossible to unlock the workstation on macOS 27

Hello,

We have an enterprise application that provides a security agent plugin with custom UI based on SFAuthorizationPluginView. We’ve been testing it on macOS 27 Developers Betas 1 through 4 and we noticed that if we set screenUnlockMode to 2, then after a screen is locked for the second time during one session, it can no longer be unlocked.

Here are the concrete steps to reproduce:

1. Open Terminal.
2. Run sudo defaults write /Library/Preferences/com.apple.loginwindow.plist screenUnlockMode -int 2
3. Lock the screen.
4. Observe the “You must enter the password to unlock the screen” dialog window.
5. Enter the correct password and press OK.
6. Lock the screen again.

Expected result:

• The dialog “You must enter the password to unlock the screen” is displayed again.
• Entering the correct password unlocks the screen.

Actual result:

• The screen is black with no visible UI.
• Rebooting the system seems to be the only way to leave this state.

Displaying custom UI at the unlock screen is a part of our core functionality and it has been working fine with screenUnlockMode = 2 since at least macOS 14. I have filed a feedback FB23918474; if it is a known issue, please merge it with mine so that I can receive updates on the matter. In the meantime, do you have any suggestions on what can be done? Thanks.