Okay, you were absolutely right! The problem was on my end.
At some point in the middle of the night Microsoft unleashed their Creator's Update and it did something weird with my sound drivers. I could hear 90% of my sounds/music just fine which made me unaware of the issue. I had uninstalled and reinstalled the older version of NCS and the problem was still there! It wasn't until I went to play an old .wav file that the same problem happened (split-second of audio and then nothing). So I re-installed my audio drivers and restarted and everything is perfect.
Now, I do have one suggestion/request (maybe warrants a new thread?) to allow a selection of one camera as a permanent audio source, so that if you accidentally click out of a camera view or if you have multiple cameras in a single room but only one with good audio then that audio remains active as you flip through the cameras.
An issue I noticed is that if I turn on the camera audio but I click anywhere in that same camera feed (not even to a new camera) the audio turns off and I have to click the speaker icon again to enable the audio feed.
Thanks again for a great product!