Try moving all your json files out to a backup folder and try again. Might be some dodgy player.json values. (I wouldn't just remove/rename it though - you might get your other json files reset by the game and lose your settings)
Actually no engine sounds outside either. I tried deletine the car folder, it reinstalled, but no help.
I had only listened to the incar and trackside sounds. They were all fine. I'll take a listen to other cams ADDED: Tried every camera choice and sound was there for all of them. One of the neat improvements is the ability now to hear the car ALL around the circuit. (this is why non-updated cars sound so loud) You can choose one of the corner camers far from your car's location and it will gradually grow in volume as it gets closer to the camera location. And I just checked the replay as well. (there is an issue with the RC not saving the proper text for a replay file. I had two replays, one very short and one longer, yet the text to choose replays was reversed. If I chose the larger file, I ended up with the smaller one loading.) But the sound was all there in replays as well. ALL the cockpit cams, spectator, even the Kite camera. I suspect you have an incorrect setting. Make sure you go to the sound options and choose 256 sound channels. Also verify you are indeed using the TEST oreca and not one of the regular ones(and...are also using the Release Candidate<just being thorough>)
I am using the regular game, not beta. And the test f pro is fine. It is only the test oreca that has the problem. I tried the regular oreca, and it is fine. All other cars i tried had sounds, it is only my test oreca that has no engine sounds, the ai test orecas DO have sounds.
The test oreca uses new sound engine features. It probably doesn't work properly using the 'opt out' rF2 version.
But the test F Pro is fine, I have sounds with that car, only the Oreca is affected. It's not a big deal, I was just curious if anyone else had this problem. And, the AI cars DO have sounds, just not MY car that I am driving.
The Oreca is the only car with new sounds. *and yes, I tested and also had no sound. The Test cars are there to test with the RC, so it's not something many will have tried...