Kerbal Space Program

When attaching the FAT-455 Aeroplane Tail Fin to a Mk. 3 Cargo Ramp, the tail fin will not respond to SAS or manual control inputs such as yaw and roll.
Also, the tail fin does not have any physical forces applied via airflow through the aero forces overlay.

The problem seems to occur when loading a previously saved vehicle with the two parts attached such that the tail fin forms a vertical stabilizer relative to the mk.3 cargo ramp.

The problem is only resolved by either moving the tail fin to a position on the side of the cargo ramp, and then moving it back, or by removing the tail fin in flight, i.e. in a crash, where the tail fin will spontaneously respond to inputs and physical forces.