Solved: Sensei blocks SNMP

[siegfried]

It seems that the Sensei plugin blocks some SNMP queries via the LAN interface. At the monitoring host SNMP checks (i.e. bandwith usage checks for network interfaces) don't get answers from the firewall box. If i press "Enter Bypass mode" at the status page for the sensei plugin in Opnsense, the checks works fine. But the strange thing is, other SNMP check (query for OID sysDescr.0) works all the time...
Running system is 19.7.2.
Any ideas/hints?

Update: I figured out that the checks works fine if SNMP v1 is used. SNMP packet size for the check was the problem. After reducing the max packet size in the service check configuration the checks are working again with SNMPv2.