Some observations

  1. I think you will find this problem is fixed in the forthcoming update. If you want to email me your project, I can take a look in a current development build and check that it looks OK. Please be sure to include the details of the layout and page on which the problem occurs to save me scrolling through a big project looking for it.

  2. You can’t move instrument change labels in the current version of Dorico, but this too will be possible in the forthcoming update. I can’t advise what might be going on with your rehearsal marks, but if you have a reproducible case, please attach it here or send it to me.