i have four zabbix proxy in one zabbix-proxy-group.
with 1800 vps, 350000 items and 8000 hosts per proxy.
Failover period for proxy-group is 3 min.

Situation:

• proxy1 was goes shutdown for mainstance
• all host from proxy1 move to another proxys in this proxy-group
• proxy1 goes up. status change to "online" in zabbix proxy group page
• proxy1 start load configuration from server 
       /usr/sbin/zabbix_proxy: configuration syncer [loading configuration]
    this process takes about 6-7 minutes.
• during configuration loading, the proxy groups page reports that proxy1 was last available 30 seconds ago, 1 minute, 2 minutes... 
• after 3 min proxy1 was goes to "offline" status. all host from proxy was move to to another proxys in this proxy-group
   At the same time, proxy1 continues to load configurations...

In this situation, proxy1 will never return to work.

Expected:
Last proxy availability checks not dependent of configuration syncer [loading configuration]