While playing splitscreen on a local environment, I've noticed two main issues:

1. If one of us are away from the controller for an extended period of time, our controllers can timeout. When We try to 'wake it' we cannot continue playing with two controllers. The game throws this error, and it will not allow the second controller to continue. It continues to replace the player one controller with the controller for player two. We need to exit out of the game, and reload it in order to continue playing split screen. 
2. The game lags incredibly when playing splitscreen, to the point where blocks will be destroyed but will remain visible for several minutes. This happens often in an extended play session. This also occurs with placing blocks, as they the space they were placed remains empty.