I don't know how to "hide" an track in Vegas. Don't think you can.
You can make it fairly small (minimize) but I don't know how to hide a track.
But a track can scroll off the screen entirely and still play.
Scroll the time line up to see if that is the case or "double" click on the "timeline scroll bars" on the far right of the timeline to "minimize" all the tracks. It may show up this way.
If none of this applies. Post a screen shot so we can see what goes on...
I actually just discovered this a few days ago, 12 years after this thread was made, while using Vegas Pro 13. 😁 The invisible audio track problem can be avoided by soloing all visible tracks (however this only prevents the invisible tracks from being heard or rendered, but it does not actually remove the invisible tracks from the project).
I wonder if this bizarre behavior was completely fixed in newer versions of Vegas. I think what might possibly trigger the bug is grouping tracks (with locked events?) and then either repositioning those tracks or dropping them into another group (so the first group loses its "grouped status"). I may never know for sure, but at least there's an in-project workaround! 😌