The "Delete" icon on clip audio tracks is missing or flaky.

I was trying to figure out how to eliminate an unwanted audio track from a clip in the Media Pool so it doesn't get rendered. It looked like an embedded audio track could only be muted, and not removed; but this wasn't true. The trash-can icon was simply missing. Later I pulled up the same clip's attributes, and there it was, magically.
This isn't just a cosmetic problem, because there's no other way to delete these tracks; there's no context menu. And if there's only one audio track, the icon never appears. This is in beta 2.
Screen grab:

This isn't just a cosmetic problem, because there's no other way to delete these tracks; there's no context menu. And if there's only one audio track, the icon never appears. This is in beta 2.
Screen grab:
