This achievement can be extremely glitchy. I had to unsubscribe from all of the workshop items and re-verify the game files for it to work.
Only the host of the server gets it.
Make a server, disable table flipping, promote the other person and then demote them and ask them to flip.
I'm not sure if the extra steps are necessary, but it takes only 5 seconds to do them, so I guess it's safer this way.
If it doesn't work, just repeat making the lobby, and maybe restart the game every few attempts.