If you can’t edit a GPO with the Management Console, there is a way to manually edit GPOs. To manually edit a GPO without the Group Policy Management Console, navigate to this location and edit the policy directly:
\\Domain\SYSVOL\Domain\policies\GPO Unique ID\
You’ll need to find the GPO’s Unique ID to know which GPO you need to edit.
You may wish to load up ADSIEdit and open the GPO’s properties (Default Naming Context -> System -> Policies, right click, then click Properties) and check that everything seems to be taken care of.