I’ve been able to reproduce Michael’s problem. Attached is a short excerpt from Bartók’s Concerto for Orchestra - on the second page I’ve adjusted a bunch of staff spacing to reproduce the score I’m working from (squeezing two systems onto one page).
Bartok-ConcertoForOrch-staffspacing.dorico.zip (415 KB)
I fiddled around with Layout & Engrave Options a lot, but I’ve still had to put in manual system breaks and staff spacing occasionally.
Anyway, you should see on the second page that the horn divisi is spaced too widely apart. Whenever I change it, after saving, closing and re-opening the file, the bottom horn divisi staff has its staff spacing cleared: it’s back to a blue handle, while all the other handles are red. Any ideas?