What causes staff spacing to reset?

I’m working on a large score and I have made edits to staff spacing and then those edits seems to disappear later. My question is: what events cause staff spacing edits to revert to their default position?

Interesting to hear, as I also experienced this…
Staff spacing in a custom score layout for choir changed without me having touched or revisited that specific layout. I had edited the staff spacing in an empty system to make more room for the other systems on that page. This „squeezing“ was gone when I exported to Pdf file. Luckily I noticed and revisited that score layout.

Did you do anything that would force an override on a frame — or did you remove any overrides already in place?

It is possible that I removed or changed something in the „main“ score. But I would not expect this to have affected the other layout.

Adding a page in the beginning of the score could cause it.

See Daniel’s reply here: Adding a blank page reset all manual staves position - Dorico - Steinberg Forums

Thank you for that link, filipedfs. I really hope this gets fixed soon! I’m working on a nine-movement piece and have finally gotten all the staff spacing correct. However, I want to add a cover page and it seems I can’t without losing all my fine-tuning work.

(BTW, thank you, Daniel and team, for listening to us so closely, with prompt, honest replies!)

You can add a cover page as a new flow. Use only one player and put opaque text blocks over the stave.

See my solution here:

If I place a new flow before an already created flow will the systems remain in their position? If this is the case, it is a good workaround.

Yes. I’ve done it for a front page.