Bloodhound's mark does not work if too much bleed is applied

I used the skill quite a bit in endgame, it worked as expected.
But ever since upgrading my damage quite a bit, the red bar starts to fill as expected, then starts to deplete rapidly (without stunning the boss), and the UI bugs out noticeably (there are many red "|" to left and right of the stagger bar)
Sometimes the red stagger bar is filled, but no stun occurs either.

Same here, Trying to inflict a stun with the mark seems to have an opposite effect