SNMPv3 Discovery Issues

[innovot]

Hello:

we have enabled discovery of a network and only a hand full of nodes are being found. we have increased the logging for the discovery daemon and see the following:

11079:20150511:094815.460 discovery: item [.1.3.6.1.2.1.1.1.0] error: Cannot connect to "1.2.3.4:161": Timeout.
11079:20150511:094815.461 End of discover_service():FAIL

Yet if we run snmpwalk from the command line it works fine. We have already tried increasing the timeout to 30 seconds in zabbix_server.conf

Ideas please ?

[innovot]

Any thoughts as to what may be wrong please ? Have ran a tcpdump on the target and see the monitoring server send a single 43byte UDP packet but that is it. As previously mentioned SNMPWALK works flawlessly on every node.