PDF Export from Book Script Ignores Auto Sized Image Frames Unless recompose() Is Called

Hi everyone,

We're running into a consistent issue when exporting a book (.indb) to PDF via script, particularly in InDesign Server workflows.

When exporting a book using a script like this:

book.exportFile(ExportFormat.PDF_TYPE, pdfFile, false, preset);

Some images inside auto-sized image frames (usually with height or height+width auto-sizing enabled) do not appear in the final PDF.

However, if we add the following logic:

var doc = app.open(bookContent.fullName, false);
doc.recompose(); //This seems to fix it
doc.close(SaveOptions.YES);

then re export the book, all images appear correctly.

what we observed 

• The frames are visible in InDesign UI, and images appear fine.

• If I export a chapter directly with indesign UI, PDF is fine.

• If I export the .indb book without recompose(), images are missing.

• This happens in both InDesign Desktop and InDesign Server, but especially affects automated flows.

So my questions are 

• Why does book.exportFile() fail to render images in auto-sized frames unless recompose() is called beforehand?

• Is this expected behavior when exporting books via script or from InDesign Server?

• Are there other layout-related updates that don’t happen unless documents are opened and recomposed?