None of these steps are working for me. Not only does "system track" not show individual beats to which I can highlight (it won't let me), when I delete beats after pressing shift B, all subsequent beats shift to the right over half a bar when I don't want them to.

There needs to be a better system for the next version of Dorico. Perhaps something like "insert pick-up" and you select the number of beats, and it appears. Done. The current steps are way too complicated and frustrating. I've already wasted 45 minutes of my time trying to figure out a solution for this.