There are bugs in this fight regarding this debuff no matter how good your positioning is. Just because you don't see them in 3 weeks doesn't mean they don't exist.
Last night, our tanks started getting rooted in place, had their buffs removed, and couldn't attack until the boss did a knock-back. First time we'd seen it in a month of tries. Stop trying to sound cool and start trying to help.
Bioware can tell you that many of the "bugs" reported are people just being ignorant of mechanics. There are going to be a few occasions where someone has something buggy happened, but unless they can post a combat log or a video to prove it, it's most likely just them sucking and lying about it... or just being ignorant.
Ever noticed how many times people have posted that the first boss in EV nightmare mode is bugged because occasionally a non tank gets one shot? These same people don't know you need to control the top of the threat table. It would seem like a bug without that knowledge, but I assure you, the debuff for zorn and toth is working fine. When someone in your raid says "I got the debuff" when they're attacking Zorn, it means either your positioning is bad or that player made a mistake.