Hi,
If Windows 11 keeps reverting to a solid color after you set a wallpaper, it usually means a background policy or cache file is interfering. First, open gpedit.msc, go to User Configuration > Administrative Templates > Control Panel > Personalization, and make sure “Prevent changing desktop background” is set to Not Configured, this allows Windows to apply your chosen image. Next, reset the wallpaper cache by pressing Windows + R, typing %AppData%\Microsoft\Windows\Themes, and deleting the TranscodedWallpaper file; then reselect your background from the Pictures folder. If it still won’t stick, run sfc /scannow in Command Prompt (as administrator) to repair any corrupted personalization components. These steps fix most cases where Windows briefly shows an old image or defaults back to a solid color.
kind regards,