Initially installed Zabbix v. 2.0.3, then - upgrades till the version 2.2.3 (with changing repo url) via YUM. Starting version 2.2.1 (as I remember, it was major upgrade from 2.0.x to 2.2.1) we found that Monitoring -> Events tab is clear and it displaying no events at whole even for "Group: all" and "Host: all", "Source: Trigger". It is bad, because we can't understand what was wrong and some Actions was not executed (remote exec cmd command on agent) or SMS was not sent.
Sometimes, when I click on breadcrumbs some events are displaying, but actually not all events (for example, the number of actual problems is 19, but only one event is shown). You can see the picture in attached screenshot.
Updating to the following Zabbix version was performed using command `yum update zabbix*` and then restart the whole server (mysqld, httpd, zabbix-server & zabbix -agent).