@J.P. Lesser, Thanks for posting in Q&A. After deploying update ring policy via Intune, we can follow the steps in the following link to confirm if the policy settings are applied on the device side.
Meanwhile, for the registry key, it seems is GPO related. When it is set. it will win over the setting in Intune. So please remove these registry kyes and only use Intune to deploy.
However, if the registry key under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\PolicyManager\current\device\Update. is already changed on device side after we deploy the policy via Intune, but it is still not working. Then the issue can be on windows side, you can contact windows support to look into related logs to troubleshoot the issue.
Hope the above information can help.
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