I didn’t realize the missing flight path in the GPS was a bug. I thought they give it to you for the first leg only. It’s good that you figured a method to keep the flight paths but I’ve been using Little Navmap to get around it as @TenPatrol mentioned.
I purchased Rafael Santos InGamePanels where one of the panels is for Little Navmap. This allows you to have Little Navmap right in the game. There’s actually a bunch of useful panels in that collection.