Friends Can't Play!

I've tried playing with my friends and they can't find any multiplayer games.  I've tried helping them but they can't play online at all.  Nobody can join their games and they can't join other multiplayer games.  I tried almost everything I know that fixes the game.  I gifted them the game, and I don't know if that was the reason why they couldn't play online.  Someone please help!  One of my friends is on MAC.

OSX currently has a different build than Windows which prevents people on OSX from joining games of Windows users.  It is important to note that someone on OSX shouldnt switch to Windows and then go back to OSX since it could mess up the saved profile.

For those on Windows, you should be able to see each others games if you host a public game or invite one another to your game through steam.

@ddace quote:

OSX currently has a different build than Windows which prevents people on OSX from joining games of Windows users.  It is important to note that someone on OSX shouldnt switch to Windows and then go back to OSX since it could mess up the saved profile.

For those on Windows, you should be able to see each others games if you host a public game or invite one another to your game through steam.

Thanks! 

Any chance this will be resolved?