I did have issues with the "In-game & microphone" setting . Have you tried just "In-game" ?
I don't have the setting turned on of always recording (Shadow time) the last 5 minutes.
Other than that I can only suggest lowering (or upping) the video quality to see if something changes.
There have also been some new drivers recently released, always worth a shot.
I always do a full install of the drivers and I think that does have some audio related stuff in it.
Same here - no sound.
Had this with Afterburner after 1.1 released. Download of Klite sorted it except for a horrible white noise for first minute or so of capture.
you installed more codecs and it fixed it? Easy enough to to test.
Also I'm using the integrated motherboard sound. Do you have a separate sound card?
Some people in a google search say to make sure NOT to install the NVidia audio drivers,
although as I've said, I do.
have you set up your speaker system correctly in windows.
https://www.youtube.com/watch?v=Pq2oj1CcD4U.
Make sure you don't use another setting your system can not handle, it can cause adverse effects like work one moment, and not the next. ;-)
Good luck.