I have the same problem and can't find a solution. I've tried each and every frequency and rebooted after each change....no luck.
Could it be a Windows (UAC) permissions problem? I just recorded with sound for the heck of it: 2017 07 04 19 12 - YouTube it is recording sound for me, but the timing is off for me (way off!). I noticed this issue earlier with Adobe After Effects (CC2017) and randomly with video playback as well - but a simple open/close of AE solved that.
I'm on on 17.6.2, Windows 10 Pro (Creators edition). It seems there is a widespread issue with previous versions of ReLive/Radeon drivers as well (check in the actual Support Forums ). Mine just started with 17.6.1 which also coincides with the Creators update. Most of my recordings and Twitch streams were flawless with older versions.