Bloodhound Mark bugged/unclear

Something is off with how Bloodhound Mark supposedly works - it seems to wear off at random even when the target has blood loss, the stun buildup from it disappears randomly sometimes, and sometimes bleeding doesn't cause any stun buildup.

The idea of it seems obvious - place on mob with blood loss/you are about to bleed, mark stays and you use it to build up stun and such, if you consume blood loss, say via Blood Hunt, the ticking down resumes until the target has blood loss again. This does not seem to be how it works in practice, however, as longer fights see the mark falling off randomly and the stun buildup disappearing.