Hello,
After seeing some peer device weirdness after upgarding my active and standby 4200v's to 11.6, I wiped the HA config and started over. I am at the stage to add a device to the peer device l...
Did you create a separate HA_vlan (self IP) for failover/config sync? (if so, try to use this IP to add the peer device), assuming it is also reachable.