Steps to reproduce:
- Navigate to Configuration of items/triggers of "Zabbix server";
- Check one or more items/triggers belonging to Mounted filesystem discovery;
- Click Mass update;
- Do some changes, e.g. change Item type to SSH agent or add a new tag for triggers;
- Click Update.
Frontend shows green box saying that item/trigger was "successfully updated".
Configuration of items/triggers hasn't changed at all.