The MalwareBytes Management Console is pretty nice vs the other competitors I have tried out.  Here is a nice walk through for an issue I had when migrating to a different server and new clients would not register anymore.  I had to go the route of uninstalling and reinstalling the client software but maybe you will have better luck:

https://support.malwarebytes.com/hc/en-us/articles/360039024813-Change-Malwarebytes-Management-Server-IP-address-or-hostname

https://support.malwarebytes.com/hc/en-us/articles/360039024493-Remotely-uninstall-managed-clients-with-Malwarebytes-Management-Console