I’ve got a system with a key change at the ending system break. Some staves are divisi, but unison in the next system (with those wonderful choir arrows).
The cautionary key change is not shown in the extra divisi staves. (each pair of divisi staves has the key change in the top staff but not the bottom).
Is this a bug or user error?
It’s a bug, I’m afraid. There are some nasty edge cases for items like key and time signatures when you transition from divisi to unison or vice versa. We have these issues on our backlog and plan to fix them, but they’re quite gnarly (which is why they’ve not yet been fixed). I can only apologise for the inconvenience caused.
I found the only way to fix this is to extend the divisi onto the next system and then hide the unneeded staff.
But I need to show the numbers …
If you move the system break away and back again (e.g. one move to the right, then one move back to the left) the time signature should appear. However, this won’t persist between sessions (i.e. you would need to print/export the layout before closing the project, and repeat if you close/reopen the project later).
That works. But unfortunately this is only an excerpt of a publication with over 160 pages. This means, I have to change this on the day before I have to export the PDF for print. Very risky … 
