Why are group policies applied incorrectly?

Question

Active Directory

Hello!
In order to apply information security regulations in my IT infrastructure and block user workstations when a certain period of inactivity occurs, I applied the following policies:
Password protect the screen saver = Enable
Screen saver timeout = Enable (900 Seconds)
Enable screen saver =
Enable after 15 minutes (900 seconds), and after exactly 1 minute. What could be the problem?

Answer 1

The problem was in time synchronization in the domain. All computers must correctly synchronize time with the domain controller.

Answer 2

there is another policy that is applied after and changes for 1 minute