The puller moves up to a moving mob, stops, turns on autoattack and most off the times the mob has moved out of range before the first hit lands. Repeat up to maximum pull distance. 
See also: https://www.redguides.com/community/threads/52843-Struggling-kissassist-noob
Possible fix : https://www.redguides.com/community/threads/52905-Possible-fix-for-melee-pulling-bug

See also: https://www.redguides.com/community/threads/52843-Struggling-kissassist-noob
Possible fix : https://www.redguides.com/community/threads/52905-Possible-fix-for-melee-pulling-bug

