After installing 10.13.3 supplemental update, cannot set a photo as desktop background

After installing the 10.13.3 supplemental update, the custom background I had set up was replaced with a generic Apple mountain landscape. When I went to settings to change it to my preferred photo, I could select the desired file, but now the background just shows up as all black, no photo at all. I tried with several different photo files, and with jpeg and png file types. I also tried to change the background by opening the files in Safari and then right-clicking - again no luck. Any suggestions?