For the past while now I've felt like there were a few times where someone had started they stunned/CC'd a mob but it did not appear on my nameplates until a few seconds later with cd lower than max or sometimes where it looked like stuns were removed randomly.

I looked through my clips and found an example of it looking like it was being removed and reappearing:
https://streamable.com/3s2d1d

Kidney shot disappears immediately and doesn't re-appear:
https://streamable.com/2haa9h

Hammer of Justice never shows on the enforcers nameplate but is on target unit-frame (very last debuff):
https://streamable.com/601vu1