Knockbacks in PVE on NPC don't fully work
I know we found an issue in CoE with Alpha. On the first encounter the ranger would point blank shot him into the corner. After a patch he would just fall over instead (with out defiance stacks of course).
We found that if the ranger shot him once to engage him then fired point blank he would go flying backwards but otherwise the push back didn’t work.
I have no idea if there are know bugs to devs about some of these knock backs or if they have been tweaking things but yes there are some on going issues with them.