Hi, good day!
I would appreciate it if you could answer the questions below.
Are you using a personal, school, or work computer? Also, are you signed in with a personal, school, or work Microsoft account?
When was the last time it worked properly?
If you're using Pro edition, please try the method below.
Press Windows key+R to open Run then type: gpedit.msc
Press Enter
Navigate to the path below
User Configuration > Administrative Templates > Start Menu and Taskbar
Find and double click the policy named "Remove and Prevent Access to the Shut Down Command".
Change the setting and select either "Not Configured" or "Disabled" and click OK
Close Group Policy Editor
I look forward to receiving your update and I'm willing to collaborate with you till we resolve the issue. Do keep me informed by clicking "Add comment" below.