Welcome to the Community,
with only a screenshot but no configuration details or log files it's hard to say what's causing the issue. Anyway what you could try is to restart the Management Services on the host from the DCUI and - if this doesn't help - disable HA and then re-enable it.
Btw. although it may work to use the IP addresses, you should consider to create Host-A records for the hosts in your DNS server and manage (add to vCenter) the hosts by their FQDN names.
André