Not sure if the command grab functions the same as the rock pickup, but I noticed while in the training room that enemies behind kragg but inside the circle grab-hitbox from the command grab are not getting picked up. This is most notable on smaller characters and causes me to whiff when I would think the grab should be landing.
Not sure if being in front of kragg is a requirement in addition to being in the command grab-box. But since kragg can grab the rock this way and there are no notes I've found saying there is the "in-front" requirement, thought I'd call this out.