Hello JoeD_PS,
Thank you for posting in Microsoft Community forum.
Did you sign in the non-working machine and the working machine using the same end user? If so, how did you perform "Run as Administrator"?
Did you click the same App or program and then perform "Run as Administrator"?
Please do some tests as below and check if the user policy or machine policy control the setting "Run as Administrator".
You can try to sign in the same machine using different end user and check the "Run as Administrator" on the same App or program. Check the result.
You can try to sign in the different machines using the same end user and check the "Run as Administrator" on the same App or program. Check the result.
I hope the information above is helpful.
If you have any questions or concerns, please let us know.
Best Regards,
Daisy Zhou