I find the best solution to be:Ĭopy all of the pictures you want from the folder you have in (e.g. I get the issue that if I choose slideshow for the lock screen 'you need more than one picture in this folder for slideshow' This has happened to me a number of times over the years, usually after a version update. , updated to windows 10 v1903 and the lock screen issue has re-appeared.
