Hi,
Hope everything is going well.
1,Please check your group policy to see if the windows update setting is pointed your SCCM SUP. If there is one, please disable it to have a try.
2,On the test co-managed devices, go to Settings -> Updates and Security -> Windows Update -> Advanced Options, then click View configured update policies, then verify that the policy type is Mobile Device Management or Group Policy.
3,If the Windows Update Ring policies are successfully deployed by Intune to the co-managed devices, you will be able to see the settings in the Registry under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\PolicyManager\current\device\Update. Refer to below guide:
Support Tip: Troubleshooting Windows 10 Update Ring Policies
Also check registry keys under:
HKLM\Software\Policies\Microsoft\Windows\WindowsUpdate\AU
and HKLM\Software\Policies\Microsoft\Windows\WindowsUpdate
Hope it helps. Have a nice day!
Best regards,
Simon
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