Compile Ignoring Front & Back Matter on second compile

I have a Scrivener project, stored on Dropbox, that has front and back matter.
If I select go to the Compile window and select the Front & Back Matter and then compile to PDF the resulting file includes the Front & Back Matter. If I then immediately do another compile, without changing the Front/Back matter, the front and back matter folders are ignored and some default (?) is used.
It’s my understanding that the Compile options should be preserved across compiles. Am I misreading the documentation or is this a bug?

The front mater consists of three text files for a dedication, forward and a Scrivener constructed table of contents (Edit > Copy Special > Copy Document as ToC).
The end matter is a text file with a single line of text.

Version: 3.1.5.1 (2073405) 64-bit - 06 Jul 2023
Windows 10

I wanted to attach a screen grab of the Compile window but apparently I’m no allowed to. However, it does look very similar to the examples I’ve seen. The appropriate check boxes are checked and the fields contain the right folders names.

Are you Compiling with a Filter, Collection or Binder Selection? That might rule out Front and Back matter.

If the Filter icin above the right hand side column in the Compile Overview window is colored blue, you’re using a filter.

Hope this helps

Thanks for the suggestions. I’m not using a filter or a collection.
So I tried selecting the document in the binder and it exhibits the same behaivious.

Are your files available offline (Dropbox setting) ?

Could perhaps explain your case.
1st time → Scrivener loads them
2nd time → Scrivener “thinks” it has them, when in fact it doesn’t, because they are not available offline, but Scrivener doesn’t “ask” for them on this second compile.

Anyways, - hypothesis aside -, if you use Dropbox, your files MUST be set to be available offline. In all cases.

I checked and files are available offline (I checked the settings AND the file dates on the local copies of the files on 2 machines).

I may trie rebuiding the project from scratch tomorrow to see if the problem goes away. It could be crud in one of the .scrformat files (?)