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If Zabbix server and proxy servers are on different time zones (at least 1h interval between them) then there is issue with queue and data processing. Affected are items who has set  "Update interval" to 0 and "Custom intervals" is set to "Scheduling" with interval greater than 1h between checks, for example "wd1-7h0-23/2". Item type is "Zabbix agent", haven't tried with other item types.

Steps to reproduce:

1. Set up server and proxy in different time zones - at least 1h difference.
   1. 1xZabbix Server - "Europe/Oslo", PHP-FPM timezone "Europe/Riga".
      1xZabbix Proxy - "Europe/Riga". 
      Databases on both servers are PostgreSQL 14 and their time zones are "Europe/Riga".
2. Add one host, that gets monitored through server and other through proxy.
3. Add few items to both hosts with different custom scheduling intervals "wd1-7h0-23m0-59/5","wd1-7h0-23/2","wd1-7h0-23/2","wd1-7h0-23/3","wd1-7h0-23/4" and with update interval set to 0.
   1. With the first to scheduling intervals there are no issues. With others however it get's interesting.
4. Wait till data get's gathered.
5. Check "Latest data" and "Queue details" for inconsistencies.

Result:
Latest data:

Queue:

Item configuration:

Expected:
Item execution time get's synchronized between Proxy and Server.

Queue uses same time (Zabbix server or Epoch) for item processing - not important if item get's monitored by Zabbix server or proxy servers in different time zones.

If neither of previous is possible and this behavior is by design, then please mention workaround in Zabbix official documentation.