@olivierlambert I just wanted to point out how I solved this issue. It happened to me when I had a host kicked from a pool while the host was offline and I manually re-added it. Long story I was remote and didn't want to reinstall via IPMI. What I did after joining the pool and seeing that no iSCSI IQN information was showing either in the general page in xcp center or via this

xe host-list uuid=<host uuid> params=other-config

I left the pool and re-added via XOA. I think I ran into it with a bad join and leaving the re joining rebuilt all of the appropriate configuration files.

All the best and massive kudos for such a great product.
-Travis