If we check the next day, then the file is unlocked.
If we click to unlock the file, then refresh, it's still locked.
This is a production system, and is affecting our user's ability to collaborate.

To clarify, I meant the only time the file becomes unlocked is by waiting the next day.

Peter,

Thank you for the email. I've set the windows OS timezone setting on the App server and DB server to the same timezone, which has fixed this issue.