Inserting pages apparently shifts vertical spacing?

[pianoleo]

Inserting pages has always removed vertical spacing adjustments, as these are tied to the page, not to the music. For clarity: they are indeed tied to the music frame, but when you insert pages, the music frames themselves don’t move - just what’s contained within them.

This has improved a little in recent updates (see Vertical spacing + page insert request - #4 by Lillie_Harris for instance) but you’re best off either adding prefatory pages before you start laying out the music, or constructing them in a text editor and prepending them at the PDF stage (as I last typed this morning:)

@pianoleo

If you’re building a contents page or a cover page, either do that first - or at least put in placeholder custom master pages at the front of each part - or commit to doing that job in a word processor or other third-party application. If you insert pages at the beginning, later, you’re likely to lose any changes that are tied to individual pages: staff spacing’s the obvious one (and it’s rare you should need to tweak that manually, but even so).