I have this same issue.
I'm running FreeNas 11 RC
I created a ZVol under my ZPol, I can see a VNC port.
When I click start vm, says VM started and once the page refreshes it stays as STOPPED and VNC or TightVNC cannot connect.
Console:
Jul 18 20:20:15 myfreenas tap0: Ethernet address: 00:bd:4b:80:17:00
Jul 18 20:20:15 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:20:15 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:20:15 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:20:15 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:20:15 myfreenas kernel: tap0: promiscuous mode enabled
Jul 18 20:20:15 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:20:15 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:20:15 myfreenas bridge0: can't disable some capabilities on em0: 0x1
Jul 18 20:20:19 myfreenas dhclient: New IP Address (em0): 192.168.1.175
Jul 18 20:20:19 myfreenas dhclient: New Subnet Mask (em0): 255.255.255.0
Jul 18 20:20:19 myfreenas dhclient: New Broadcast Address (em0): 192.168.1.255
Jul 18 20:20:19 myfreenas dhclient: New Routers (em0): 192.168.1.1
Jul 18 20:20:19 myfreenas kernel: em0: link state changed to UP
Jul 18 20:20:19 myfreenas kernel: em0: link state changed to UP
Jul 18 20:21:17 myfreenas tap0: Ethernet address: 00:bd:88:72:18:00
Jul 18 20:21:17 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:21:17 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:21:17 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:21:17 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:21:17 myfreenas kernel: tap0: promiscuous mode enabled
Jul 18 20:21:17 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:21:17 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:21:17 myfreenas bridge0: can't disable some capabilities on em0: 0x1
Jul 18 20:21:21 myfreenas dhclient: New IP Address (em0): 192.168.1.175
Jul 18 20:21:21 myfreenas dhclient: New Subnet Mask (em0): 255.255.255.0
Jul 18 20:21:21 myfreenas dhclient: New Broadcast Address (em0): 192.168.1.255
Jul 18 20:21:21 myfreenas dhclient: New Routers (em0): 192.168.1.1
Jul 18 20:21:21 myfreenas kernel: em0: link state changed to UP
Jul 18 20:21:21 myfreenas kernel: em0: link state changed to UP
Jul 18 20:24:25 myfreenas tap0: Ethernet address: 00:bd:6e:50:1b:00
Jul 18 20:24:25 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:24:25 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:24:25 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:24:25 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:24:25 myfreenas kernel: tap0: promiscuous mode enabled
Jul 18 20:24:25 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:24:25 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:24:25 myfreenas bridge0: can't disable some capabilities on em0: 0x1
Jul 18 20:24:29 myfreenas dhclient: New IP Address (em0): 192.168.1.175
Jul 18 20:24:29 myfreenas dhclient: New Subnet Mask (em0): 255.255.255.0
Jul 18 20:24:29 myfreenas dhclient: New Broadcast Address (em0): 192.168.1.255
Jul 18 20:24:29 myfreenas dhclient: New Routers (em0): 192.168.1.1
Jul 18 20:24:29 myfreenas kernel: em0: link state changed to UP
Jul 18 20:24:29 myfreenas kernel: em0: link state changed to UP
Jul 18 20:24:40 myfreenas tap0: Ethernet address: 00:bd:db:8b:1b:00
Jul 18 20:24:40 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:24:40 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:24:40 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:24:40 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:24:40 myfreenas kernel: tap0: promiscuous mode enabled
Jul 18 20:24:40 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:24:40 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:24:40 myfreenas bridge0: can't disable some capabilities on em0: 0x1
Jul 18 20:24:44 myfreenas kernel: em0: link state changed to UP
Jul 18 20:24:44 myfreenas kernel: em0: link state changed to UP
Jul 18 20:24:44 myfreenas dhclient: New IP Address (em0): 192.168.1.175
Jul 18 20:24:44 myfreenas dhclient: New Subnet Mask (em0): 255.255.255.0
Jul 18 20:24:44 myfreenas dhclient: New Broadcast Address (em0): 192.168.1.255
Jul 18 20:24:44 myfreenas dhclient: New Routers (em0): 192.168.1.1
Jul 18 20:25:00 myfreenas tap0: Ethernet address: 00:bd:5c:db:1b:00
Jul 18 20:25:00 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:25:00 myfreenas kernel: em0: link state changed to DOWN
Jul 18 20:25:00 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:25:00 myfreenas kernel: bridge0: link state changed to DOWN
Jul 18 20:25:00 myfreenas kernel: tap0: promiscuous mode enabled
Jul 18 20:25:01 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:25:01 myfreenas kernel: bridge0: link state changed to UP
Jul 18 20:25:01 myfreenas bridge0: can't disable some capabilities on em0: 0x1
Jul 18 20:25:04 myfreenas kernel: em0: link state changed to UP
Jul 18 20:25:04 myfreenas kernel: em0: link state changed to UP
Jul 18 20:25:04 myfreenas dhclient: New IP Address (em0): 192.168.1.175
Jul 18 20:25:04 myfreenas dhclient: New Subnet Mask (em0): 255.255.255.0
Jul 18 20:25:04 myfreenas dhclient: New Broadcast Address (em0): 192.168.1.255
Jul 18 20:25:04 myfreenas dhclient: New Routers (em0): 192.168.1.1
Ubuntu iso: ubuntu-16.04.2-desktop-amd64.iso
The issue is with the VM not starting at all, I know I have to do some extra configuration with grub to be able to install it after the VM starts.
TIA