Microsoft has confirmed that a Windows 8.1 Preview bug doesn’t allow users to change the lock screen wallpaper, with the default photo shown on all affected machines.
According to a post on the company’s support forums, the issue occurs regardless of whether you are using a local or a Microsoft account to sign into the computer.
“More importantly, the issue occurs after changing the lock screen background 8 times. From the 1st to the 7th time, the lock screen displayed the correct image that the user selected. On the 8th time, the lock screen displays another previously selected image as the background image,” one user explained.
A Microsoft engineer confirmed the issue and said that the company is already looking into it, which means that a fix should be released either in the coming weeks or before the RTM version hits the market.