Another one,

Every now and again during the escort missions the ship I arrive back at the Tiger Claw to discover that the ship I'm escorting has decided that the Tiger Claw is for pansies and turns around to go back where it came from.

I usually get it sorted out, eventually, but I don't understand what's happening or how I'm actually fixing it.

Anyone know the answer to this?

Maybe you fly too far from the escorted ship? You should stay reasonably close to it. Use autopilot to get to the next waypoint (when you do so, you should see all three ships moving together).