Hi there, John W Walker.
This problem can be caused by your router NAT settings or your TV cable you use.
NAT is usual multiplayer problem that players cannot join to each other*. * this is about online multiplayer in Xbox Live.
I can provide you link to solve that issue, here it is
support.xbox.com/.../nat-error-solution
If that is not multiplayer (online) and you talking about split screen feature this problem can be caused by your connection cable to your TV. Are you using HDMI cable? If you are not using HDMI (Using standard A/V cable, VGA or YPbPr) you will not able
to use that feature because Minecraft support Split Screen feature only on HDMI.