Steps to reproduce:

1. Reboot the network device monitored via SNMPv3

Result:

Item zabbix[host,snmp,available] still returns 1, but other data is not collected.
Clearing the snmp cache on proxy doesn't help in some cases, restart of the proxy is required. Sometimes running "check now" on all SNMP items o the host helps.

Expected:

Zabbix should resume data collection on rebooted network device after clearing SNMP cache.