bhyve with lagg failover doesn't work on wifi

I'm using bhyve on 11.0-BETA2, bridging tap0 to lagg0, a failover
between wifi and ethernet.  The bhyve VM's networking only works I'm
using ethernet.

> # Lagg config.
> ifconfig_em0="up"
> create_args_wlan0="wlanaddr 3c:97:0e:46:70:ca"
> wlans_iwn0="wlan0"
> ifconfig_wlan0="WPA"
> cloned_interfaces="lagg0 bridge0 tap0"
> ifconfig_lagg0="laggproto failover laggport em0 laggport wlan0 DHCP"
> # tap0 and bridge0 are for bhyve.
> ifconfig_bridge0="addm lagg0 addm tap0"

With the ethernet cable connected, the VM's networking works.  But when
I remove the ethernet cable and lagg0 fails over to wifi, the VM can no
longer use the network.

I can use tcpdump to see the DHCP packets going along this path:
    vtnet0 -> tap0 -> bridge0 -> lagg0 -> wlan0

The DHCP requests appear on wlan0.  But the router never sees them.

Here's the ifconfig output when wlan0 is active:

> em0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
>         options=4219b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,WOL_MAGIC,VLAN_HWTSO>
>         ether 3c:97:0e:46:70:ca
>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>         media: Ethernet autoselect
>         status: no carrier
> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
>         options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6>
>         inet6 ::1 prefixlen 128
>         inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
>         inet 127.0.0.1 netmask 0xff000000
>         nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
>         groups: lo
> wlan0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
>         ether 3c:97:0e:46:70:ca
>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>         media: IEEE 802.11 Wireless Ethernet MCS mode 11ng
>         status: associated
>         ssid neural_network channel 1 (2412 MHz 11g ht/40+) bssid c4:04:15:90:f5:fd
>         regdomain FCC country US authmode WPA2/802.11i privacy ON
>         deftxkey UNDEF AES-CCM 2:128-bit AES-CCM 3:128-bit txpower 30 bmiss 10
>         scanvalid 60 protmode CTS ampdulimit 64k ampdudensity 8
>         -amsdutx amsdurx shortgi -stbc wme roaming MANUAL
>         groups: wlan
> lagg0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
>         ether 3c:97:0e:46:70:ca
>         inet 192.168.1.17 netmask 0xffffff00 broadcast 192.168.1.255
>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>         media: Ethernet autoselect
>         status: active
>         groups: lagg
>         laggproto failover lagghash l2,l3,l4
>         laggport: em0 flags=1<MASTER>
>         laggport: wlan0 flags=4<ACTIVE>
> bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
>         ether 02:4a:6b:6e:fc:00
>         nd6 options=9<PERFORMNUD,IFDISABLED>
>         groups: bridge
>         id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
>         maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200
>         root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
>         member: tap0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
>                 ifmaxaddr 0 port 6 priority 128 path cost 2000000
>         member: lagg0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
>                 ifmaxaddr 0 port 4 priority 128 path cost 55
> tap0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
>         options=80000<LINKSTATE>
>         ether 00:bd:ea:f0:f6:00
>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>         media: Ethernet autoselect
>         status: active
>         groups: tap
>         Opened by PID 1322