Solved Lock Screen sometimes does not display selected picture (just goes black)

Using Windows 11 Pro Version 23H2. The system is up to date. Sometimes (maybe 10% of the time) my Lock Screen and Sign In Screen fail to display the picture I have selected in Settings/Personalization. The screen is simply black, but I can sign in with no problems. I am using one of the default Windows 11 pictures for my Lock Screen. Any reason why this is happening?

Hi & welcome,
I have had it happen as well, but not to the same frequency as you are reporting before I started to use
a free, small, non-intuitive application that makes sure you have your lock screen and desktop how you want it to be.
It is called Dynamic Theme. You can find it in the MS Store.