I've been trying to find out about this issue and have found lots of suggestions about sound lag or general absence, but my issue is simple.
As soon as I click into the multiplayer option, the sound disappears.
This makes races impossible.
I have checked the sound devices. It still occurs regardless of the use of speakers or headphones.
I have checked out the Win10 communications setting, and it is set to 'do nothing'.
Still the problem persists.
Does anyone have another suggestion?
I like the career mode, but would like to play against humans.