@Daniel Carey, Thanks for posting in our Q&A.
From your description, I know you have deployed an Intune policy but does not work on targeted device.
Based on my research, I found that the setting type of Prohibit access to Control Panel and PC settings is User, which means the policy should be assigned to user group instead of device group. Please assign the policy to a user group and check whether it can work.
Hope it will give you some ideas. If there is any update, feel free to contact me.
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