When the identification timeout value in the User-ID Agent is set to 45 or 55 minutes, the user-to-IP mapping is flushed frequently. If the User-ID doesn't reestablish mapping for every user, users have to log into the domain again for the mapping to appear.
The user identification timeout values can be changed to delay the mapping from being flushed, or the user identification timeout can be disabled.
Go to User-ID Agent
Go to Cache Either increase the User Identification Timeout or remove the check from the Enable User Identification Timeout.