This is an odd issue we are having, but I'm not sure how to fix it.

After 45 minutes or so, we start to get a buzz in our audio. Our directors often listen to the direct feed so we sometimes don't hear it until it's been happening for a few moments.

If I right click on the audio box in vMix and select "reset," it will go back to normal and the buzz goes away. Any reason for this? Any fixes?