Some images won't export to PDF/Image link is broken

I’ve “Tropied” issues of a magazine I’m researching. I’m trying to export each magazine issue to a single pdf. For the most part it works, but there are some images that won’t export. I can see the image in Tropy, but in the pdf it shows up as a broken link. (From the attached example, I was able to make a pdf of the other pages of the magazine without a problem.)

Just to be sure: does this photo show normally in the image viewer?

If it does not, then the reason is probably that Tropy can’t open the original anymore. If it does show in the image viewer, then it must be related to printing only. In that case, can you check if changing the ‘optimize images for printing’ setting in the preferences makes a difference?