Ones for a time (not every time)
After problem occurs, IT Services view does not reset alert in elements, that not linked to the Trigger. (I mean not always reset alarm, usually it works fine, but for some reason not always).
In that case, there is alarm but there is no Reason explained, and when you check -all monitored parameters are OK. (check screens)
We already delete all IT services and create all of them again, it didn't work, we check logs in debug mode -> no errors
We use 1.8.5 performance items so we know, that we don;t have any problem with performance of any processes.

At this point we are going to create a trigger like ping 127.0.0.1, that will be always true to link with groups that does just grouping other groups or triggers, hope that will help, but if there is possibility to create empty IT services that only groups other "leafs", it should always work. And it isn't.
IT will be hard to recreate, sometime, problem with no reason clear itself, but usualy we need to change something to force Zabbix to generate true alarm (like change IP to not existing), Zabbix will discover problem, generate alarm, then we restore IPO to real one, Zabbix clear itself from down to up -this is manual force Zabbix to check again, often without manual "push" it clear itself alter few hours, but we use SLA, and we have people that really use IT Services view, and the few time that this problem kick in, is really troubling.