Taunt mechanics in general doesn't work as intended

Preamble: I wanted to try a Champion build with Replica Trypanon. As champion ascendancy provides both ways to 100% taunt on hit and then taunted enemies can not evade attacks. To trigger taunt I'm using shock nova and then herald of thunder as soon as I shock the first pack. I spotted that I still miss a lot.

So I blamed my setup because it's not always cealr whether a mob was struck by HoT already and thus taunted and can not evade attacks.
So I conducted a series of experiments with hitting a new pack with shock nova and then hitting them to see if I can hit them all immediately. It also worked in like 50%-70% cases, not in 100% stated in the ascendancy description.

So I simplified experiment again, assuming that maybe taunt on hit is not 100% reliable, which would mean that the problem lies in the 'Conqueror' part of the Champion ascendancy. Thus I took several warcrly skills, and repeated the experiment using those as a source of taunt. The percieved effect was also about 50%-70% success.

Visual indication was also in accord to what I stated above: mobs that were missed after supposedly being taunted were not gloving red.

I did all experiments while still leveling my character, in act 6 on white mobs.

While reading forum threads on this topic: people are complaining on the specific taunting cases, like inability to reliably taunt with totems having a specific totem mastery, but this experiment hints that the problem might have much larger scope.