Hello,
I ran into a similar issue few days ago: Onehost sync temporary failure
All my hosts were in the INIT or UPDATE state. After pulling hair over this issue, I have rebooted the server where ONe daemons run, which I planned to do nevertheless because of Meltdown/Spectre updates. Since then, the host monitoring work as expected - the hosts are in the ON state. So maybe restarting all ONe daemons can help?
-Yenya