Error: "You do not have permission to perform this operation. Access is denied" when trying to edit a GPO (4234704)

When trying to edit a GPO the following error occurs:

"You do not have permission to perform this operation. Access is denied"

If you click the down arrow next to Launch Editor, and enter credentials, the same error occurs. 

This can occur if the account does not have sufficient rights to edit GPOs, or if the account cannot be authenticated. 

To test, checkout the GPO, ogin to the machine where you are running the GPOAdmin client, as the same account that you have been trying to use, and launch GPMC to confirm you can see the GPOs. Try to edit the Working Copy that was created by checking out the GPO. 

If you are not able to login as the account, using an elevated command prompt, perform a runas to run GPMC as a different account:
runas /user:domain\username cmd

Then from the command prompt, run GPMC and test as above.

If you are not able to natively run GPMC and edit the Working Copy GPOs created by the account, GPOAdmin will not be able to function as it uses the native GPEdit to edit GPOs.