Items from LLD "Datastore discovery" for "Average read\write latency of the datastore ..." become "Not suppoted" with one of this errors:
"Performance counter data is not available." or "Performance counter instance not found."
After Zabbix server\proxy restart items become supported
The error was preceded by a migration of virtual machines. Some virtual machines was turned off.
There are errors for hypervisors items on which we did not find changes in the datastore or hv itself in vsphere log