Lock screen stuck on image, even after trying to change it

[Dadstar0410]

Since switching to the Tech Preview, I've had one image on my lock screen. I can't change it. I tried the mmc hack to force a specific lock screen image, too. Still the same image on my lock screen. I can't change it in settings, because I've tried that too. And it only happened with that one picture. Before this happened, I was switching lock screen backgrounds without a problem. Can anyone help me, i.e. has anyone had the same problem and can tell me how to fix it please?

 

[Kloyd Angelou Turado]

I don't know if this us a similar incident, but there are built-in lock screen images that I cannot set in my 1520. Whenever I do, it reverts back to the default "marbles" wallpaper. I can only choose a few lock screen wallpapers from the selection.