I have 6 MS-250 switches in two stacks of 3. My monitoring still uses SNMPv3 - network is configured for SNMPv3 username and password match my monitoring system. I have tried re-adding the credentials to the dashboard no change.
I then ran a packet capture on the switch up link for port 161 and I can two traffic. Interestingly the response from the switch in the pcap report authentication and privacy parameters "Missing"
From the switch to monitoring system packet. It has the correct username as configured on the dashboard.
But when I poll from my monitoring system SNMP Discovery fails.