It works, but very slowly, same with pull. I've experimented with some small "tugboats" since I tend to send turrets careening off into space pretty often and need to retrieve them. One of the problems with pull being once you get something going towards you it keeps going. So you need a stop beam as well to make a tractor.
I have noticed that my little 10 module beams will work on even small cruisers (around 2k) but it takes a while, and we're talking the kind of speeds that come from lowspeed collisions, and of course no one is flying them.
TLDR: You probably just need a bigger array. I'm curious how it works against a ship applying thrust since I only play singleplayer I haven't been able to test.