My mistake @Vincent_Vincent
Yes, my problematic document, inserted into @AmberV’s *.scrivx, compiles as it should, with the correct page breaks.
As for your instructions, I just don’t understand clearly what you mean:
Once done, restore your compile format’s location in the “My formats”
Sorry, but I don’t see the email address 
In the email, apart from the file and the link I’m going to send, what do I need to tell them? Just direct them to this page?
Do you compile with a compile format that you have tweaked yourself or do you use one of the factory defaults without any alteration to it ?
If you compile with a factory default compile format, don’t worry about it. They’ll only need the project.
windows.support@literatureandlatte.com
Link to this thread in the email.
But I am pretty sure AmberV will intercept it.
I use a compile format tweaked by myself.
OK, Hang on, I’ll switch computer so I can produce screenshots.
You want the compile format you are using to be set like this, so it is saved along the project in the backup.
If it isn’t currently like that and you end up changing it, you’ll have to change it back once the backup is done (the file you’ll send LL’s staff) so that it is available in your other projects as before.
That’s the “Once done, restore your compile format’s location in the “My formats”” part you asked me to better explain.
You may even lose it if you forget. So this is important.
. . . . . . . . .
You could also simply export it and attach it to your email just like the backup.
If you already know how to do this instead, might as well.
…And in case you don’t, here’s how :
“Testing” is my demo format, you select yours in the list and do the export as indicated at the bottom of the screenshot.
This gives LL’s people a tiny bit more work, but it is completely safe for you. No risk of losing your compile format.
Ok, this is so crazy I’m ashamed of myself…
I tried to copy the Compile Format as you said @Vincent_Vincent and suddenly, Scerivener sent a message that I didn’t have time to read and crashed.
I looked in the Settings → Compile Formats folder and it was empty. (Later I realized that the format file was saved in the wrong scrv folder, but before that…)
I decided to compile in an old format that I had built myself and that I had used at the very beginning of my Scrivener experience and tadãaãã… everything was fine. The page breaks were correct.
As far as I’m concerned, I won’t bother trying to understand the problem, because I don’t want to revert everything to the wrong format. I’m just going to modify the format to my personal preferences, noting down all the changes step by step so that I can revert it if something goes wrong.
However, so that your time hasn’t been wasted, and if you have an “academic” interest in identifying the error with the problematic format, I’ll send it to you anyway.
I can’t thank you enough for your support and patience, nor apologize for the time you’ve wasted on me.
Let me know if you want me to send you the file.
Thank you so very much.
Cheers 
You are welcome.
→ No time was wasted ←
I am glad your issue is somewhat fixed (but the crash part is…)
As far as I could read, the message was related to the “location of the file”, but I was trying to choose the folder to save the file in, I wasn’t trying to open it, so I don’t understand what the location has to do with it. Then the message disappeared and Scrivener closed.
Yeah, I’d be happy to take a look at the compile format and see if it causes issues. Thanks!
Hi @AmberV
I’ve emailed you the file to windows.support@literatureandlatte.com
Thanks for everything
Thank you, I got the file and it looks like we do have a bug here. It is a little elusive in that it doesn’t act the same in other tests I created that are similar, but at least in this case, I found how to toggle the bug on and off at will: it is the Override text and notes formatting setting, in this particular case, that is damaging the page break. If I turn that off, then the page break works.
Of course if I turn it off it also doesn’t format the book correctly in 12pt Courier, so that’s not a really good solution all by itself. I came up with this workaround for you, that should be sufficient:
Project ▸ Project Settings... and select the Section Type category.+ button and create a Type. Call it whatever you want, I’ll use the example, “Special Scene”.File ▸ Compile... and if you scroll through the preview column in the middle, you will find that “Special Scene” is using the default “As-Is” layout, which is exactly what we want it to be doing, since this section is already formatted.Give that a spin, and see if it solves the problem for you. It worked for me in the sample copy of the project you sent, using your original compile Format unmodified. Meanwhile I will get this data added to the ticket we already have on this issue, so as to make it known that it can happen with more than just styled text under some conditions.
Thanks for sending us what it takes to see it, that really helps find these sorts of bugs.