I am having an issue with 1 PDF file in which there are images that are dropping from the page when ripping to a digital press (iGen3). I have tried re-pdfing the file because that has helped in the past with fonts not printing correctly because they were not embeddedd when the customer created the pdf.
Same issue happened whether printing to the press or re-pdfing the file, a gray box appears in place of the graphic.
We found a work around where we drop the file in a hot folder for the press. File is supplied from customer as pdf, we do not have the native files. sample images below: 
