Steps to reproduce:

1. Zabbix Proxy HA Group have 6 Proxys in the Cluster
2. Zabbix Agent Config files have proxys on the config:
   Server=zbxproxy01,zbxproxy02,zbxproxy03,zbxproxy04,zbxproxy05,zbxproxy06
   ServerActive=zbxproxy01;zbxproxy02;zbxproxy03;zbxproxy04;zbxproxy05;zbxproxy06
3. On the Host Menu, if i specify one Zabbix Proxy, instead of Proxy Group, the host will change to this Proxy, but after some time(seconds) the hsot go back monitored by my Proxy Group

Result:
See screenshot...

Expected:
If I specify one Proxy, the host can`t change to do Proxy Group