This problem is known and there already have been threads about this problem when there’s an instrument change… You should probably search the forum. But still, someone will probably chime in and help you.
It’s on the Team’s radar, for what it is worth (and it’s not nothing, with that Team)!
Quote from Daniel Spreadbury: Rests can go missing when you have instrument changes within a bar, which is a limitation at the moment; we plan to address this at some point in the future but I can’t say when it will be.