Custom static route not applied at reboot

Hi,

I have a FreeBSD 13.0-RELEASE-p4 system that runs openvpn in a vnet jail to
create a site-to-site VPN.  This works great except for one detail: I want
the host system to add a static route to send traffic for the other side of
the VPN to the IP address of the vnet jail to use it as a gateway.  I tried
this in rc.conf:

static_routes="vpn"
route_vpn="-net 192.168.0.0/24 10.0.0.225"

This is trying to add route -net 192.168.0.0/24 10.0.0.25.  On reboot, this
route is not present in the routing table and must be manually added.  When
it's manually added the vpn works great.

I'm using the igb driver; searching around I saw an ~recent errata about it
(https://www.freebsd.org/security/advisories/FreeBSD-EN-20:09.igb.asc) that
didn't look super relevant(?)

I don't think that the jail need be alive and running for the host to add a
routing table entry so I don't think this could be a startup race
condition.  Is that right?

Can anyone tell me what I'm doing wrong here or give me an idea of what to
investigate?

Thx,
Scott