I have tried the following:
1. Disabled the Host - Remove the host - then reconnect the host to the cluster. Issue remains
2. Disabled HA on the cluster. Then re-enabled HA on the cluster. Issue returns.
The cluster errors with: vCenter Server is unable to find a master HA agent in Cluster....
The Host errors with: vSphere HA agent for the host has an error: vSphere HA agent cannot be correctly installed or configured. vSphere HA cannot be configured on this host because the SSL thumbprint has not been verified. Check that vCenter Server is configured to verify SSL thumbprints and that the thumbprint for this host has been verified.
When I go into the vCenter Server settings for the SSL, and enable the checking for verified ssl certs, there are no servers listed for me to verify the thumbprints.