@AndrewT I have been able to reproduce the issue. However, I do notice that it stops once you enter gameplay and the announcer says "Welcome to Mars". It can also be reproduced when in-game by going to the planetary view and dragging the map, and again it clears when you exit that view.
Additional testing: If you haven't entered gameplay and the sound is looping, return to the main menu > options > will stop the sound from continuing to play
Additional testing: If you haven't entered gameplay and the sound is looping, return to the main menu > options > will stop the sound from continuing to play