It happens on 1.47n. It does not appear to effect the sound at all.
I discovered it happens when I press the M key to turn on/off the music as well, however, it seems that when this happens initially;
it seems to happen every time I open the (experimental) editor a new, then play test. The music is switched to off and when I press M to turn it on it's at full volume. I can go and open the player separate to adjust the volume and it'll work for a while but it will happen again.
When it happens the setting in the file goes to 0. I had the sound volume at 31, and music at 19. When it resets it goes to 0, yet is actually playing at full volume.