Motion Vectors not working for Server players?

I've looked around and can't find a solution to this. A few of my procedures involve motion vectors, and all work perfectly fine on single player, but when I test it with another player in a LAN world, his motion vectors do not trigger, and my motion vectors that should affect his movement do not work either. Basically targeting other players doesn't work and as a server player, they do not work.

I have one procedure that does seem to work though, one that essentially bolts a player in the direction they are looking. I think it works because it has no "after 20 ticks on server side do" blocks. But I need help figuring this problem out! It is essential for my Mod in order to be able to play multiplayer.