On log /var/log/lightdm/lightdm.log appear this:

[+278679.48s] DEBUG: Seat seat0 changes active session to 
[+278680.63s] DEBUG: Seat seat0 changes active session to c5
[+278680.63s] DEBUG: Session c5 is already active

I don’t know what is happening exactly, but seems that try to active an unknow sesion, really it’s activated good, but reappear password screen for a correct activation of session.

Can you guide me what to try?