Hi Chris,
EasyNAS does not support bridge networking on KVM out of the box, there are many missing packages that are required in order to make it work.
I tried playing a little with setting up a bridge, and manage to create one however when I add an interface to this bridge I got the same result ( ip is gone )
both bridge and KVM are cool features that I really want to see in EasyNAS, but we are not there yet.
I promise to put it in my roadmap in one of a future release.
Thanks.
Yariv.