Steps to reproduce:
1) Open the latest attached project.
2) Open scene 'Solar System'.
3) Press 'Play'.
4) In the Hierarcy, expand the children of 'Earth'.
5) Select 'Audio Source'.
6) Expand '3D Sound Settings' in the Inspector.

In the scene, the audio Listener is attached to the Main camera and the Audio Source is a child of the Earth game object, as it is moving relatively to the Listener, its distance is not updated in the '3D Sound Settings', unless the Inspector window is updated (by changing values, scrolling etc.).

Reproduced on:
5.5.0a5, 5.4.0p1, 5.3.6p2, 5.2.4f1
OSX, Windows and Linux.