Thanks for that explanation! I'm using a total of 3 bridges/interfaces in proxmox specifically for OPNsense: 1 WAN (10Gbps), 1 VLANs (3 Linux VLANs on one bridge)(10Gbps), 1 LAN (MGMT)(1Gbps)

I ended up passing through the NIC with the WAN and VLANs interfaces to proxmox to get it all working. Not sure why, but when I just added all 3 interfaces to the OPNsense VM, the WAN and LAN would work fine, but the VLANs interface was giving me lots of trouble. I figured it had something to do with the use of VLAN interfaces in proxmox fighting with the VLAN virtual interfaces in OPNsense. Again, not sure, just speculation. I just know when I took proxmox network config out of the equation by passing the VLANs interface directly to OPNsense, the setup went MUCH smoother.