"Minimum Gaps" are not minimum gaps

[asherber]

You’re right about what “minimum gaps” means. However, there is a circular reasoning issue which can affect some frames/systems and can keep Dorico from providing the expected results.

„Resolve the collision..” strange behavior

The problem here is that Dorico does not know exactly how much vertical space the music is going to occupy until it has cast it off, but it cannot know exactly how to cast it off until it knows the height of the music, so this is an inherently circular problem. When the 'Automatically resolve collisions between adjacent staves and systems’ option is on, then Dorico makes an estimate of what it thinks the height of the system(s) is likely to be prior to casting it off, so that it can decide when…

That seems to be what’s happening in your case. If you look at the frame fullness indicator in Engrave mode, your first page is at 114%; Dorico won’t normally produce a page that overfull. My guess is that Dorico estimated that it could fit 4 systems on that page, respecting your minimum gaps, and then ran into problems making it happen.

If you add a frame break at the beginning of the 4th system, things will look much better. (Though it seems to me that everything looks a little tight with that spacing. You may be happier either increasing the inter-system gap so that Dorico only puts 3 systems on a page, or reducing your space size so that each system is a little smaller.)