So, I changed the hostname in the QMC for the Central server in a multi system deployment of Sense. This caused a Error 500 message, and I then stopped the services, deleted the certs, and restarted the services. The QMC comes back up fine.
However, now the local host (meaning the Central node with QMC) row now shows as "Unknown, never contacted". Obviously, this is not cool. Editing the entry shows that it fell back to the old hostname (which is fine).
Any thoughts? I don't want to do anything else at this moment until this stabilizes.