Hi,
I've got similar issue here.
I've setup site to site wireguard with wg0 interface and gateway to be able to route back from servers to office . In the office router I've got various static routes to reach different servers segment through the Wireguard gateway.
It works as expected but if I reboot OPNsense traffic is not passing through tunnel until I toggle on/off wg0 interface manually.
I've got similar issue here.
I've setup site to site wireguard with wg0 interface and gateway to be able to route back from servers to office . In the office router I've got various static routes to reach different servers segment through the Wireguard gateway.
It works as expected but if I reboot OPNsense traffic is not passing through tunnel until I toggle on/off wg0 interface manually.