Split-screen on Minecraft: Xbox 360 Edition (Title Update 12+) requires specific conditions. Even with an HDTV, it often fails due to version mismatch or settings.
Verify: Main Menu → bottom right shows "Xbox 360 Edition" + Title Update number (e.g., TU73).
Test on another TV. If works there, your TV's scaler/EDID is incompatible with 360's 480p/720p split output. No fix except different display.
Note: Xbox 360 Edition servers (Realms, external servers) shut down 2023. Local split-screen still works offline.