Did quick search and couldn't find similar reported.
Using PC version 1.7.0.57
I have a double sided A4 leaflet - I imported to AP as a pdf and saved as a AP doc.
Loaded AP format doc and exported to pdf (print ready, 300 dpi).
On one side there are six square images in two rows. The top row in the resulting pdf the images appear as negatives - see attached - bottom row are fine. Note, all images appear correct in AP format doc.
I then tried exporting as a pdf (print ready, 400 dpi) same result, top row of images as negatives, bottom row ok - then tried exporting as a pdf (flatten, 400 dpi) and this was fine, all images appearing as normal.
I've uploaded the AP file and the pdf.
AA X-STK leaflet - general.afpub
AA X-STK leaflet - general.pdf