I just ran slmgr.vbs /ipk Windows 2019 KMS server key in our portal. That will activate everything down. Even if you don't own 2019 you should still get the server kms key to use. I called Microsoft for the 2016 issues a few years ago and that is what they told me to do. MS licensing has always been clear as mud. Just try to within your true up windows and keep everything under SA. They wont bother you.