If this reproduces on 3.5, then it can't be related to the 3.6 Cumulative Network Statistics feature. Meni, this reproduces for you on 3.5 deployments as well?
this bug being reproduced on 3.5 by.
engine build vt13.15 > rhevm-3.5.0-0.34.el6ev.noarch
I doubt a 3.5 bug depends on a 3.6 feature.
there is a network usage data, it probably takes some time before the table is updated.
This bug not reproduced on 3.5.z(188.8.131.52-0.1.el6ev). Only on 3.6 - see BZ 1196640