Bars disappear between score & part (which shouldn't happen!)

The first bassoon player complained to me in rehearsal yesterday that there were 4 bars missing from her part. I told her that was impossible because I was using Dorico! But I was wrong… attached is the relevant page from the part in Dorico, where bars 37-40 have disappeared.. The relevant bars are all there in the score, and in all the other orchestral parts, and I couldn’t see anything in the score to indicate how this discrepancy could arise. It’s a particular problem because as things are I can’t generate a printed part with the missing 4 bars included. I did produce a combined part with bassoons 1 & 2 on separate staves, and that works OK, but I’d really like to make a proper part & learn how to stop this happening again.
Many thanks,
Stephen

It’s hard to say without inspecting the actual document.

Is there a page override, suggesting a manual layout alteration?

Are all signposts visible?

If the score and other parts are correct, then it’s something in either the Layout Options or changes to the layout itself.

All signposts are visible. There’s a frame break at the beginning of the page (and also at the beginning of the next page), but that’s all. The layout options are the same for all the orchestral parts. There are no page overrides in this part.
I tried deleting the frame break at the beginning of the next page but the same 4 bars were still missing. So I’m a bit stumped. When I have a little more time I might try making a completely new part & seeing if the same thing happens.

As @benwiggy suggests, if you can upload your project file here (you can probably remove all players except for the bassoon), then someone can take a look.

Thanks! I’ll take another look when I’m back at my desk.
I think there is basically one system of 4 bars that has been displaced, and I wonder if when I was manually ‘improving’ the staff spacing I may have inadvertently dragged it off the bottom of the page, but now I don’t know how to get it back as it’s no longer visible.

I can confirm it’s possible in Engrave mode with the staff spacing tool to drag an entire system out of the page.

Reset layout doesn’t bring it back, but Engrave->Staff Spacing->Reset Layout does !

but wouldn’t that create an Override ? the OP said there was none - curious

The OP said there were no page overrides, which are local changes to the page template.

Staff or note spacing changes are a different thing

In Engrave mode, it is indeed possible to drag individual lines outside the visible area.
However, this should be evident from the red marker (above the next line) and the unusual spacing measurements on the left.
(Translation using deepl.com)

Addendum:

It was indeed due to a system being accidentally dragged off the bottom of the page and disappearing. Weirdly there was no page override, but while tidying the part up I had put a frame break to appear on the first system on the next page. Removing this frame break and then adjusting the spacing between the systems allowed the missing system to creep back on to the page & I could then put it in the right place. It was interesting to see that a system can be dragged out of sequence (it was below the system that it should have been above).

It occurred to that it would have been easier and probably quicker, to create a new part altogether.

So any thinks for all the suggestions - I learned a lot!

As discussed above, manual staff spacing adjustments do not cause a page override.

Whenever I am troubleshooting this sort of situation, I usually go into the problematic layout and enter Engrave mode > Staff Spacing sub-mode. My procedure is to select the square edit handle attached to the top left of the first system. If it is red, I press delete, which will cause it to move to its default vertical position (as set in Layout Options, etc.). Once it is blue, I press the down arrow to select the edit handle on the next system on the page. Delete, down arrow, delete, down arrow, and so on until all the systems on the page have re-appeared and returned to their default vertical positions. Alternatively, if all of the systems are visible but are in the wrong order, I use a marquee selection to select all at once and press delete to do them all at the same time. As I mentioned in another post very recently, I have seen instances where a lower system has had a negative value for the staff spacing and consequently appeared above the preceding one.

Why not just Engrave > Staff Spacing > Reset Selected Frames?