Trouble with VLAN setup on 4-port OPNsense

[User074357]

Hi,
I have a 4-port OPNsense box to which I have my WAN, PC and NAS connected. OPT1 and OPT2 (NAS and PC) are bridged for LAN. I know it's not recommended to use a bridge for this, but I'm trying to avoid a dedicated switch for now.
The NAS is running TrueNAS SCALE and I now want to create a VLAN for some of the VMs on it. I added a VLAN interface on TrueNAS with tag 20 and the static IP 192.168.20.2/24. I then created a VLAN for igc1 (OPT1) with tag 20 on OPNsense and removed OPT1 from the bridge, since I read I cannot use the untagged interface on a bridge while also using VLANs. The goal is to use 2 VLANs between TrueNAS and OPNsense and adding one of them to the OPNsense LAN bridge.
I added the VLAN interface under assignments and set the IPv4 Configuration Type to Static IPv4 and configured the IP 192.168.20.1/24.

I was expecting to be able to ping my TrueNAS host under 192.168.20.2 from my PC in LAN now, but this doesn't work (100% packet loss). The firewall live view also doesn't show anything.

I'm new to VLANs and I know I should just buy a managed switch, but I'm confused as to why this doesn't work. Am I missing something?