Phenquestions
Windows 10 Enterprise has added many more features to the operating system. However, some users using this version have reported facing two major issues with the Lock Screen.
- Windows 10 Lock Screen is grayed out
- Windows 10 Lock Screen displays a black background.
If you are one of those who are facing this issue, this post offers some workarounds.
Windows 10 Lock Screen grayed out
There is a Group Policy setting, Force a specific default lock screen image under:
Computer Configuration\Administrative Templates\Control Panel\Personalization.
Many users are unable to modify the settings.
The reason is that possibly because of another Group Policy setting, Prevent changing lock screen and logon image is also enabled. When this policy is enabled, it grays out the controls under the Lock screen. One can see the lock screen and the image, but cannot make changes. Check the image shown below. 
If the Prevent changing the lock screen and logon image policy weren't enabled, the Lock screen would look like this.
A workaround would be to disable the group policy Prevent changing the lock screen and logon image and set updates to Force.
Windows 10 Lock Screen displays black background
In this situation, the image of the Lock screen would be blacked out without any difference to other functionalities of the Lock screen. The time, text, controls, etc. would work as normal.
To verify and resolve the issue, search for and “Performance Options” in the Windows search bar and look for the Animate windows when minimizing and maximizing option.
Make sure that this option is unchecked.
You could also Run gpedit.msc and navigate to the following setting:
Computer Configuration\Administrative Templates\Windows Components\Desktop Windows Manager
If the Do not allow Windows animations policy is Enabled, disable it.
Hope this helps.
Microsoft is aware of this issue and has in a blog post, explained the issues in detail, and posted these workarounds. In fact, they did release an update on 24th May 2017 to fix these issues, but some are still facing this issue.
