That is definitely a bug:

If as a peacekeeper I grab or get grabed on stairs by a PK, and the peacekeeper is below me, when he puts his bleeds, it just does not apply the debuff at all.

I doubt it is a graphic glitch as in the end I don't die randomly or the ennemie does. Might be due to a difference of Y during the animation which renders the debuff application impossible to complete?

Hope it will be noticed before release.