Lose ability to do anything other than walk and type on mac client in game

This has happened to me twice now and has lost me 2 games which would have been easily won. I am not entirely sure what causes it but the two times it has happened have occurred with Rek'sai. Both times I was E'ing in onto someone on the enemy team and was killed whilst casting spells. When I respawn I can do nothing other than type to the people in my game and move my champion around. I cannot even buy items or open the escape menu, and have to force quit the game and reconnect.