I had my work laptop rebuilt recently after having numerous faulty components replaced. After the rebuild, the Windows lock screen remains black and doesn't show the background image. I changed it to a static image rather than the Windows spotlight. Unfortunately, this didn't resolve the issue.
The answer for fixing this is actually very simple, but not obvious. To correct the problem, open the System properties window by opening Windows Explorer and right clicking on This Computer and then clicking on Properties (or by pressing Win + Pause|Break).
Once the System window is open, click on Advanced system settings: