HA not being disabled at host remediation

I recently upgraded my esxi5.5 install to a new 6.5 VCSA and then the hosts.

Since the "new" install of venter, and adding the hosts into the new cluster, if I try to remediate hosts to perform updates, the status just sits at around 33% doing nothing, and the host never goes into Maintenance mode.

After trying different things, it seems that I have to manually disable HA.  Once done, the host will happily go into maintenance mode and remediate.

Then if I manually enable HA, all is good.

I only have vSphere Essentials so no DRS option available, but in the remediate settings, everything is set for Disable.

Any ideas?

Under 5.5, the disabling of HA was automatic, so I literally hit remediate and off it went.