SNMP polling from device connected to switch

I monitor a pair of SN2100 switches via SNMP from an external host. snmp-service on the switches is configured with listen-address(es) in the mgmt vrf and the service runs as snmpd@mgmt.service. External SNMP access works fine.
I want to additionally monitor these switches from a LibreNMS virtual machine running on a Proxmox cluster whose hypervisors are attached on swp (well, bond/mlag in reality) ports on the same SN2100 pair, but cannot get a response to snmp queries as I can from the external host. I’ve tried removing the vrf definition associated with the listening-address of the VM to no avail.
The LibreNMS VM can poll any device upstream of these switches without issues
Suggestions/advice welcomed!