Multiplayer Minecraft on Xbox 360
Solution 1:
Is your second controller synced to your Xbox 360? If this controller is not synced the console will not take inputs from it and the "Start" button cannot be used to load a second player into the game.
Refer to this guide on how to Sync your Xbox 360 controller
Alternatively, you may have reached the maximum amount of players on your Minecraft world. On Xbox 360 there is an 8 player limit on a Minecraft multiplayer world. If you attempt to exceed this by adding a 9th player via split-screen you may be prevented from having them join.
If that doesn't work try restarting your game or console.
Solution 2:
- Make sure all controllers are on and logged in.
- If this is not the problem, try pressing start a few times anyway, it doesn't always show up.