Config Sync issue (both boxes are staying "disconnected")

Found this topic while troubleshooting HA issues in our lab. I would put emphasis on two things:

1) Use NTP server(s) for both peers.

2) Make sure when adding a peer that you're using it's HA VLAN dedicated IP. Verify currently configured confisync-ip (list cm device DEVICE_NAME configsync-ip) - I believe this was the main reason our configuration wasn't working.

In our case we had an IP from our internal VLAN listed there (from 172.16.x.x range in our case), and even though we were able to "dicover" peer by using its HA VLAN address (from 192.168.x.x range) the devices stayed out-of-sync (Disconnected state).

Once we changed configsync-ip configuruation to match HA VLAN address it worked like a charm.