[Death Knight][Blood] Death Grip does not trigger the buff from Sephuz's Secret

[wow156]

WoW Freakz spell link: https://www.wow-freakz.com/spells.php?spell=49576&name=death-grip
https://www.wow-freakz.com/item_finder.php?item=132452&name=sephuz-s-secret
Bug description: "Death Grip" is a loss of control/interrupt spell, yet it does not trigger the buff from the legendary ring "Sephuz's Secret". In the following video, you can see that sephuz procs once used a death grip (not even used to interrupt). Yes, the video is from 7.3.5, BUT, as far as I know, there are no major changes from 7.2.5 to 7.3.5 when it comes to death knights and especially no changes for death grip.
Proof: Video from retail (first 20 seconds)

Additional links:
Patch notes for 7.3
Patch notes for 7.3.5

[Plaguesynth]

There is also a similar situation currently happening with Gorefiend's Grasp it doesn't proc Sephuz's either even tho it should .

Spoiler:

https://youtube.com/watch?v=lO_bNYyBfb4&t=835:

In this video on 0:12 the DK Uses Gorefiend's Grasp which is basically a Mass Death Grip and it triggered Sephuz's .