If nothing works to fix the Run as Administrator not working on Windows 10, then there might be some issue with your User account. So, to fix that issue, you need to create a new user account or guest account. With that, you will get an entirely new user

Fix- Can’t Change Account Type to Administrator in Windows 10 Run a particular Program as administrator by default in windows 10 Fix- Device Manager is blocked by administrator in Windows 10

If right-click Run as administrator option in context menu is not working in Windows 10, then you need to take a look at the suggestions to fix the issue.