Hello BillArtmik
It is indeed strange, and the fact is that you should be able to edit those policies as administrator. I wouldn't discard that there are other management and administration issue on this computer, so in case of a enterprise environment you may want to look into saving user data and reimaging.
In your case, the only workaround I can think of is to reset all Local Policies using an elevated command prompt and run:
RD /S /Q "%WinDir%\System32\GroupPolicyUsers" && RD /S /Q "%WinDir%\System32\GroupPolicy"
then run a gpupdate /force to load the domain GPOs
If you get any access denied error or 0x5 that would mean that your user has not enough privileges to manage local policies.
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