In case it is useful to anyone.
I found the problem.
The permissions on the ovirt hosted-engine for the /etc/pki/ovirt-engine were
root.root
I changed them to ovirt.ovirt and I was able to add the host without issue.
I have no idea why root ended up being the owner of that folder.
There was no hint anywhere in the logs that I could see indicating that there was a
problem with these permissions.
All is good now.