Thanks for your reply Lillie_Harris!
Sorry to but in on this older conversation, but I have the same problem, and I don’t think any of the solutions offered work. See below.
For unclear reasons [* A bug is suspected, but I will post this separately when I have time to do it properly *] my A trumpets don’t have a sub-bracket. I’d like to put that back in, but the staff is empty (and condensed) and there seems to be nothing I can select to add the sub-bracket back in. Bar-lines are connected across staves…
Ok, sorted. I went to write-mode. Put a note in. Back to engrave, add the sub-bracket. Back to write, delete the note. 