In split screen multiplayer, buttons aren't consistently working. It happens frequently when both players go through a nether portal at the same time and has happened a few random other times as well. Iron door is placed with a button to open it, and pressing the button does not activate the door. Save/quit and come back in will restore the button to working order.
Cleaning up old tickets: This ticket has not been updated recently (~7 months+) so is being closed as Cannot Reproduce. If you feel this is still a valid issue and is affecting the most recent versions, then please comment, or create a new ticket following the Issue Guidelines.
Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki