Just checked numerous films from the last few FSO's and BOG and none have engine noises anymore.
Excuse me if this has been mentioned, I searched and only found much older threads.
I've got the same thing, so I down loaded AH to my laptop and ran a film file , the same on on both my gaming machine and my laptop, laptop the file had sound. The gaming machine doesn't. sound stopped after the release with the B-29
copied the sounds folder from my laptop to my gaming machine and now have sound , it's the default sounds, but it works.