Default Clock on lock screen behaving weird

I am on NAE stock rooted with MF9 bootloader (no Knox) which I flashed to a few weeks ago.

I have been having a weird problem that's getting worse... I have a lock screen with a PIN set up. The big clock above the pin pad is disappearing or is not updating to the correct time some of the time. The clock in the notification bar above it is always correct. This problem is getting progressively worse. Restarting the device doesn't seem to help. Other than this issue the phone seems fine. Any ideas?