autologin-user-timeout=10 causes authentication manipulation error and breaks (disables) lightdm process

[Steve-Newcomb]

Running on up-to-date, 2-day-old installation of Artix on Lenovo P1 Gen4.

If I uncomment autologin-user-timeout= in /etc/lightdm/lightdm.conf and set it to 10 (I didn't test other values), lightdm enters a state in which it refuses to allow passwords to be typed in. In /var/log/lightdm/lightdm.log, I see:

[+0.31s] DEBUG: Seat seat0: Display server ready, starting session authentication
[+0.32s] DEBUG: Session pid=10338: Started with service 'lightdm-autologin', username 'music'
[+2.57s] DEBUG: Session pid=10338: Authentication complete with return value 20: Authentication token manipulation error
[+2.57s] DEBUG: Seat seat0: Switching to greeter due to failed authentication
[+2.57s] DEBUG: Seat seat0: Creating greeter session

The feedback to the user suggests the password was the problem; baffling. I resorted to trial-and-error to isolate the problem.

Workaround: Comment out autologin-user-timeout= . Then restart lightdm: sv restart lightdm. (The autologin feature works, I think, but its timeout option is well and truly broken, at least in Artix-land.)