Unbound ignores outgoing interface

[thisisme]

Hey

I have a Wireguard tunnel with conditional (firewall rule based) routing. I would like to force unbound through the tunnel. I'm used to pfsense configuration. All I had to do there was setting the "Outgoing Network Interfaces" in unbound. On my opnsense configuration this option does nothing. The requests are still send via the default/wan interface.

What did I miss.