Windows maintains a local cache of all the GPO settings that are applied to the system. I’ve occasionally seen this cache become corrupt or de-synchronized with the domain controller. This can cause a variety of problems including Group Policy settings not being able to update.
The Windows local Group Policy cache is located at: C:\ProgramData\Microsoft\Group Policy\History
Note that this is a hidden folder. Delete out the contents of the History folder; do not delete the folder itself.
After that, run a GPUpdate /force from command prompt to rebuild the cache. I also recommend rebooting the system at this point.