What kind of user account are we using to register the lookup service ? Remember To register to vCenter Server or SSO Lookup Service, you must have administrative rights. Are we sure DNS/NTP is working properly in this setup ?
I have try register lookup service url with email@example.com and I was found error message but I have try register with same user for vcenter so it has status "connected and green "
I have try to Check DNS and NTP, they were normally (Test NTP sync vcenter and nsx manager and dns solve their name were correct) .
VMware Support checked and show vmdir state read-only and change state to normal then lookup service become connected.