Thanks Tim! With more people having a seemingly similar issue I re- opened it as New and subscribed ubuntu-server to take a look at this again.
** Changed in: dnsmasq (Ubuntu) Status: Invalid => New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2055776 Title: After updating ubuntu, the network to which the subnet address is assigned does not become active in KVM. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/2055776/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs