Anyone else having issues with Hunter's Mark?

[:1]Mostly just noticed this in DS, but while dpsing the boss the dot for the mark will be up and then it just completely disappears. Yet the icon that floats above the target remains there. Is the debuff actually falling or being removed and why? Similar thing seems to happen with serpent sting and the dot will just disappear even though it's only halfway through it's tick time.

Was there a change with how dots and debuffs work on bosses now, or do the new bosses just have a cleansing effect?
I've noticed this too but what I realized it's because we have another hunter using hunter's mark and it overrides the one you put up. MM hunters are especially good at this.
If that was the case shouldn't I be seeing the smaller hunter's mark debuff image under the boss's nameplate next to the larger images that denote my debuff's on the boss? Because that isn't happening either.
I haven't been seeing the smaller one either with MM hunters I just noticed my hunters mark would fall off when there was another MM hunter in the raid. Just figured it was because the hunter MM talent putting up automatic hunters mark. Also happens with surv hunters just assumed the same thing...?
So thinking it might be the Marked for death talent overriding the hunter's mark when it procs?
It's possibly and addon issue. I don't seem to be having the same problem.
It's if you have other hunters in the raid applying it.

If you put a mark up, the icon will show up, however if another hunter puts it up, it will override yours. However, you still get the buff from theirs even though it doesn't show up.

This confused me a lot at first too. On the Ultraxion fight, me and another hunter constantly kept reapplying the mark, because neither of us knew about this, so we thought it was initially just disappearing.

So, if you see the debuff disappear, just check to see if it still has the red arrow. If so, you should be still be benefiting off of its effects.
Had this issue the other day, was in 10m with another hunter so I figured that had something to do with it. I also wasn't seeing her SrS marked on the mob when I knew she wasn't forgetting to cast it.
Check Interface - Buffs & Debuffs
Make sure the last one is checked off (show all enemy debuffs). Your Hunter's mark Icon won't disappear anymore (and you'll see multiple applications of SrS if you're with other hunters)