Re-Join SCCM Client to Intune for Co-Managed join Type

Hello,

I have been using SCCM for a long time, I have it is setup for Co-management, and all my workloads are moved over to Intune.  I have a few clients that for one reason or other have not been added to Intune.  I can get them onboarded, but the join type always ends up Intune.  I am trying to find out the correct recipe to reenroll an SCCM client to Intune.

I have tried uninstalling the SCCM client and reinstalling.  I have tried removing registry keys for Intune to ensure it joins again.  I have used DSREGCMD to leave and join back.  I have completely removed from Domain and deleted from Intune.  I have tried combinations of all of these things together.  I have yet to come up with a specific order to do them in.  I still think there is some remnant that is preventing a rejoin.

Does anyone have details that help me to get systems to rejoin via SCCM?

Some may say what is the difference.  The difference is there are tools that are not present if the Join type is incorrect.  

Best regards and thanks.