Unable to Connect Mission Planner to ArduPlane

I’m using Mission Planner and MAVProxy for communication with ArduPilot. Despite successfully running MAVProxy and having it listen on 127.0.0.1:14560, Mission Planner is unable to connect. It just says “Mavlink Connecting…” I’ve waited for a couple of minutes but nothing happens. I’ve tried changing ports but the issue persists. Any advice on how to resolve this connection issue?