ipv6 on genet0 + bridge not configuring

Hi,

My RPI4 is running pretty happy with some VNET jails on it.
# uname -a
FreeBSD rpi4 14.0-CURRENT FreeBSD 14.0-CURRENT #15 main-9c0287e092: Fri Nov  5 10:48:20 CET 2021     ronald@rpi4:/home/ronald/dev/obj/home/ronald/dev/freebsd/arm64.aarch64/sys/GENERIC-NODEBUG  arm64

# cat /etc/rc.conf
hostname="rpi4"
cloned_interfaces="bridge0"
ifconfig_bridge0="addm genet0 SYNCDHCP"
ifconfig_genet0="up"

I now added this line to rc.conf:
ifconfig_bridge0_ipv6="inet6 accept_rtadv"

This does trigger some ipv6 negotiation on start up, but also some errors.
bridge0: Ethernet address: 58:9c:fc:00:3e:aa
Created cloe interfaces: bridge0.
lo0: link state changed to UP
genet0: link state changed to DOWN
genet0: promiscuous mode enabled
bridge0: link state changed to DOWN
rtsol: cap_llflags_get() failed, anyway I'll try
rtsol: sendmsg on bridge0: Can't assign requested address
genet0: link state changed to UP
bridge0: link state changed to UP
rtsol: sendmsg on bridge0: Can't assign requested address
rtsol: sendmsg on bridge0: Can't assign requested address
Starting dhclient.

Dhclient for ipv4 works well and assigns an address.

Similar setup on another FreeBSD 14 works well with ipv6. But that does not have a bridge. It just enables IPv6 on the interface.

What am I missing? Something obvious?

Regards,
Ronald.