When setting the Slideshow option for the lock screen in Personalisation settings, you may bump into The Wallpapers folder isn’t supported because of its location ...

I can't figure out how to repeat it exactly but about 20% of the time when I try to full screen/slideshow a single pic in Preview, it goes to a full black screen. It's only ever happened the very ...

If you do not like the default lock screen settings, you can change them using the Windows Settings panel. Although the options are limited, you can personalize them according to your requirements.