FIXED! Changed encode mode on rendering from NV encoder to Mainconcept AVC and everything went smoothly.
I've shared a video of this issue in this post on reddit: https://redd.it/15ojjkn
I'm using Vegas pro 19.
I've tried changing a number of settings in preferences/audio device to no avail. I've also tried dropping my project into a new timeline. I've also dragged the length of my audio to expand past the selected render area. No change. The error is not with my playback software, but also appears in social media playback and in Vegas itself if I drag the rendered clip back in.
I found another post from 8 years ago reporting the same issue with no resolution: https://redd.it/2qns75
Anyone have a fix for this?