We are very keenly aware that users are waiting for important bug fixes for the new features introduced in Dorico 2.0, and you will soon have them: we are in the middle of the holiday season and key members of the teams both in London and Hamburg are away at the moment, but it is our intention to have the update with you in the next couple of weeks. In addition to fixing quite a number of bugs, there are some useful new features, and we are very excited to get the update into your hands.
The behaviour Craig has reported concerning doing Select All followed by Delete leaving behind lots of red time signature signposts is counter-intuitive, but it is for the time being the expected behaviour (and has been that way since before Dorico 1.0, as far as I know!). When you select a single barline and hit Delete, a time signature signpost is left behind because there is still a bar division there, if there is an earlier time signature that has yet to be countermanded. So when you select the whole flow and hit Delete, it is like deleting all of the barlines individually, and Dorico creates overridden time signatures at each of those rhythmic positions. It’s a side-effect of the fact that bars have to be brought into existence specially in Dorico rather than all of the music being fundamentally organised into bars.
If your goal is to remove all the music, I’d suggest either deleting and recreating the flow, or selecting the first bar of the flow and typing Shift+B to open the bars popover, then type e.g. -1000 to delete (nominally) 1000 bars (if your flow is shorter than 1000 bars, the whole thing will therefore be deleted), or using the new system track to remove everything.