I'm not sure what I managed to do, but I've never had it happen in all my decades of using Vegas. I was editing a Mardi Gras parade in multicam mode. I finished my edit, went to expand back to multiple tracks, and somehow along the way all the video tracks got muted, but thing is, they aren't muted, neither at the event nor track level... though if you look on the timeline, the tracks are darkened as if they're all muted. I've checked every track to make sure nothing is solo'ed, no dice. Here's a video of what it's doing
Have tried: Saving and rebooting Vegas.
Creating a new video track and adding generated media.