I also had trouble with an older file. At first it seemed to open properly, but on exporting, many of the images did not export, while some embedded pdfs exported only partially.
I could fix it by
- rasterizing the pdfs
- disabling all filters
- disabling all adjustments such as opacity
I don't know if the problem is because it's an older file or if these problems would persist if i rebuilt the file from scratch in the current version ....
I can share the file in a personal message but not on the forum.