I hope I can explain this coherently…
I have a piece from a client I’ve been working on. It has a ‘free’ section in the middle, and the hide and show staff visiblity seemed a good way to show all three players in all the parts just for this quite short section, having assigned all players to every part, and hidden the music for the others, except for this ‘free’ section.
To make sure that this section starts at the beginning of a system, I used system breaks to adjust that, and some previous staves to make for a good layout, plus page turns.
In these sections, where the other two players are hidden, I have found on a few occasions that the multi-bar rests revert to single bar rests, even though they are empty in this particular players part. Worrying to begin with, but I found that I could reinstate the multi-bar rest by making the same music ‘fit on one system’, even though the layout remained the same.
I will add, that the file originated in Sibelius, and was imported as an xml file.
I am able to email the file, but I couldn’t make it publicly available.