bwfm0 no networking when combined with trunk (Raspberry Pi 4)

Hello,
I have setup a trunk combination on my Pi 4 to aggregate the ethernet
port (bse0) with the wireless port (bwfm0) using the examples in the
documentation:

$ cat /etc/hostname.bse0
up

$ cat /etc/hostname.bwfm0
join "MyAp" wpakey "blablabla"
up

$ cat /etc/hostname.trunk0
trunkproto failover trunkport bse0
trunkport bwfm0
inet autoconf

And with the ethernet cable plugged in, I have networking through it:

$ ifconfig
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 32768
index 3 priority 0 llprio 3
groups: lo
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
inet 127.0.0.1 netmask 0xff000000
bse0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu
1500
lladdr e4:5f:01:0e:a8:7f
index 1 priority 0 llprio 3
trunk: trunkdev trunk0
media: Ethernet autoselect (1000baseT full-duplex)
status: active
enc0: flags=0<>
index 2 priority 0 llprio 3
groups: enc
status: active
bwfm0:
flags=8b43<UP,BROADCAST,RUNNING,PROMISC,ALLMULTI,SIMPLEX,MULTICAST> mtu
1500
lladdr e4:5f:01:0e:a8:7f
index 4 priority 4 llprio 3
trunk: trunkdev trunk0
groups: wlan
media: IEEE802.11 autoselect (VHT-MCS0 mode 11ac)
status: active
ieee80211: join MyAp chan 36 bssid 30:93:bc:e3:e8:f4 -46dBm
wpakey wpaprotos wpa2 wpaakms psk wpaciphers ccmp wpagroupcipher ccmp
trunk0: flags=808843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,AUTOCONF4>
mtu 1500
lladdr e4:5f:01:0e:a8:7f
index 5 priority 0 llprio 3
trunk: trunkproto failover
bwfm0 port 
bse0 port master,active
groups: trunk egress
media: Ethernet autoselect
status: active
inet 192.168.1.16 netmask 0xffffff00 broadcast 192.168.1.255
pflog0: flags=141<UP,RUNNING,PROMISC> mtu 33136
index 6 priority 0 llprio 3
groups: pflog

But as soon as I remove the ethernet cable, I get no networking with
the wireless access point

$ ifconfig
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 32768
index 3 priority 0 llprio 3
groups: lo
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
inet 127.0.0.1 netmask 0xff000000
bse0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu
1500
lladdr e4:5f:01:0e:a8:7f
index 1 priority 0 llprio 3
trunk: trunkdev trunk0
media: Ethernet autoselect (none)
status: no carrier
enc0: flags=0<>
index 2 priority 0 llprio 3
groups: enc
status: active
bwfm0:
flags=8b43<UP,BROADCAST,RUNNING,PROMISC,ALLMULTI,SIMPLEX,MULTICAST> mtu
1500
lladdr e4:5f:01:0e:a8:7f
index 4 priority 4 llprio 3
trunk: trunkdev trunk0
groups: wlan
media: IEEE802.11 autoselect (VHT-MCS0 mode 11ac)
status: active
ieee80211: join MyAp chan 36 bssid 30:93:bc:e3:e8:f4 -45dBm
wpakey wpaprotos wpa2 wpaakms psk wpaciphers ccmp wpagroupcipher ccmp
trunk0: flags=808843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,AUTOCONF4>
mtu 1500
lladdr e4:5f:01:0e:a8:7f
index 5 priority 0 llprio 3
trunk: trunkproto failover
bwfm0 port active
bse0 port master
groups: trunk egress
media: Ethernet autoselect
status: active
inet 192.168.1.16 netmask 0xffffff00 broadcast 192.168.1.255
pflog0: flags=141<UP,RUNNING,PROMISC> mtu 33136
index 6 priority 0 llprio 3
groups: pflog

Do I miss something?

Nothing particular in dmesg, it's running 7.1 aarch64.

I've tested the bwfm0 interface without being put in trunk, it works
fine.

-- 
David