If you want to use a different Credential Provider, you must set the ZCM Credential Provider to Disabled by setting -> "DisableZENCredentialProvider"

Once that is done...then everything should just work.....

If NOT....there may be agent corruption related to an OS Upgrade.
Try uninstalling and reinstalling the ZCM Agent....make sure to select the option to remove CASA.
Then install agent and make sure the key is still there.

If you end up needing to reinstall agent to fix along with reg key...then we can work on trying to Fix the agent....but most likely it is just the registry key is all you need to make everything work.