When assigning the proxy groups for hosts one by one from web frontend, 
the hosts were distributed unevenly. 
 
I believe they should be assigned more evenly.
Also this result would be different form the description of manual.
 
https://www.zabbix.com/documentation/7.0/en/manual/distributed_monitoring/proxies/ha?hl=Proxy%2Cgroup%2Cproxy
Host reassignment
 
Steps to reproduce:
 
1. Create 1 proxy group
e.g.)pg1
 
2.Create 3 proxies
e.g.)p1,p2,p3
 
3.Create 6 hosts
e.g.)h1,h2,h3,h4,h5,h6
 
4.Assign the proxy group for each hosts 1 by 1 from web fronent.
 
Result:
Assigned 4 hosts for p1.
 
p1:h1,h4,h5,h6
p2:h2
p3:h3
 
Also See attachment.
 
Expected:
 
p1:h1,h4
p2:h2,h5
p3:h3,h6