Hi Zep,
Definitely not. All the testing I've been doing is on missions with +2 level and counting as 2 heroes/villains. At level 47, this was mobs in the 48-50 range, including the usual spread of minions, lt., bosses, elite bosses, etc.
I was suspicious that it had something to do with the fact I'd just slotted an Expedient Reinforcement set of level 50 in the pet, and thought maybe it was something buggy with respect to the set being 50 while I was 47 (even though this should be fine, and the set had nothing to do with the KB->KD enchancement from the Universal Damage set). But I've levelled since then and there is no change. Tested both the Universal Damage KB->KD, as well as the one from the Knockback set, and the behaviour is identical with respect to the pet. It is simply ignoring the KB->KD enchancement and is sending mobs all over the place (an amusing mission he managed to push an Illusionist so far down a hall that I had 3 more Illusionist bosses adding to the fight...was quite the experience :). And to reiterate, it definitely wasn't doing this prior to the last patch. Something has changed.
I can confirm that the KB->KD enchancement is working as expected in Power Burst, it's just the pet, and in particular the Illusion Control Phantasm pet (and the decoy it creates). I don't know how pervasive KB is with other pet users, or how often the slot to remove it, although I'd expect a lot of people do given how averse groups are to having mobs flung all over the place. Was happy to hear someone else pipe up confirming they're experiencing the same problem as it's definitely a thing, at the very least for the Phantasm pet.
Here's hoping it is something trivial and easy to rectify.
Cheers,
~N