if matchmaker doesnt find the second game after finishing the first when it times out and kicks you back to the lobby it expects player 2 to go ready although in splitscreen mode you dont have the ability to go splitscreen...
Hey /u/russkil12 we're tracking this issue here on our Trello page, and will update it once a fix is out. Thanks for your patience!
https://trello.com/c/EjMdWmPv/1626-split-screen-ready-up-issue