macOS Sierra desktop picture reverts to default

You have set the picture for one day ( 24 hrs ) , it will be permanent up to 24 hrs , as soon the time crosses 24 hrs it will definitely go to default settings .Because there is no setting to save desktop picture for more than one day .

It happens on my MacBook Pro as well, I have four desktop spaces and in some of them the picture will do as I tell it in the System Preferences and in others it will revert back to the default picture. It will revert without needing to restart. I have the Desktop & Screen Saver preferences set to choose a random picture from an album in Photos, and to change the picture every 5 seconds. In one of the problem spaces, the screen will change to one of the pictures in the folder, after five seconds it changes back to the Sierra default, then after 15 or 20 seconds it will go back to the same (not random) picture from my folder, then five seconds later back to Sierra.

Fiddling around, it will work and switch background photos correctly, the I'll go to another space and, using the same album, have it choose a random photo every 30 minutes. It reverts back to the Sierra default...

The problem is frustrating because it is not reproducible.

MacBook Pro (15-inch, Mid 2012) macOS Sierra (10.12.2)

Same problem here. Trying to simply set the laptop and external display to Solid Gray. "Change Picture" is NOT checked. On restart the laptop display is gray but the external display reverts to the default sierra image. Worked fine in El Capitan...

Programmers need to say what they mean. If it says "Every" day then we expect the background image to change from images in the the chosen folder EVERY DAY. If it means keep image up for 24 hours then it should say so. Whoever is in charge of this part of the OS needs to get his act together.

In my case, I have change picture turned off (unchecked and it still does this. I have three monitors on a new video card. The other two do not change