In this project I’m working on, everything looks fine on the first page. On the second page, I added a condensing change, and I think it’s responsible for the layout that gets messed up, e.g.: (the bar numbers of the below system are hovering somewhere in the system above).
If I add another condensing change or a system break somewhere on the system below it becomes even more cluttered and chaotic:
What would be interesting would be to see the left bottom corner with the vertical filling percentage. I think your page is overfull, which sometimes Dorico does not handle very well in order to avoid some circular calculations that would make it very slow. A simple frame break would solve the issue (if you don’t want to change the space size). Or change the Layout options>Vertical spacing>Ideal gaps to something really smaller, but I don’t think your values are bad as they are now…
Here’s a thread where it is explained how it gets calculated. Why Dorico her doesn’t create a break i don’t know. Maybe if there are too many things that are too high low, it creates a bit of a mess.
The problem with the bar numbers in the first picture are the high notes. They push the numbers even higher. Maybe you can use a 8va just for the score and hide them in the parts?
Also the staff to staff gaps are rather small for the higher notes in bar 37.
in Dorico5 opening your file was no system overlapping, just the bar number was overlapping and page 2 was 120% full (as @MarcLarcher noticed), but you said the overlapping of system occurred after adding a manual break.
I just added a frame brake on the barline between bar 33 and 34, just before the high notes (as @Nukkul suggested). And all went nice. Also I increased the Justify distance only between systems when frame is at least 95% full. Other differences (I changed slightly the gap spacings) you can look in the library manager confronting your file with the “corrected” one
(I attach the “corrected” version here below)
I suggest to upgrade to Dorico 5, it seems to me that was some optimizations made (otherwise I cannot explain why was no collision of staves). Happy composing!