I have just started using Data Sets and all of my interchangeable graphics were saved from Photoshop as Photoshop PDFs without layers.
Now I run the export data sets command and the process stops to prompt me for importing some of these PDF files (every time they change as well!). This meant I had to click OK approximately 1000 times during the export process, which is undesirable, but the output was fine.
When I try opening the PDFs directly in Photoshop, the behaviour is the same: some open the “Import PDF” prompt and some just load directly. I would like to know what triggers this prompt, so I can avoid it in future.