Picture frame not updating properly

I have 2 photo frames that were properly updating (rotating pictures) but one has stopped rotating pictures and the other rotates (seemingly) at random. There are multiple pictures in each folder that they are updating from and the update time is set to 20 seconds. After deleting and re-creating the frames, they wil update properly for a short amount of time then stop. The photos are stored locally and not on a network drive or any removeable media.