DMSS playback problem

Hello,
I have a Dahua NVR setup, and I'm having an issue with playback. It won't play the last 30 minutes of any hour. For example, if I try to view footage at 11:17, it plays fine, but if I want to see it at 11:49, it automatically skips to either 12:01 or back to 11:20. Does anyone know what might be causing this?
 
That’s a new one
How are you playing back? Using the direct NVR interface playback ?

Are you using a 12 hr clock or 24 hr clock?
(You should use 12 hour)

There are so many variables it’s hard to know where to start.

Show a screen cap of the playback timeline of a channel
 
Are you viewing “All” recordings or just motion/IVS?
Green timeline with blue hash marks?

Show a screencap

IMG_9354.png