Question marks when trying to edit EOS Rebel XS images in DPP on Mac

[Schnee]

Recently bought a new (Mac) computer. Downloaded the driver for DPP onto the Mac and tried to edit some images that I took with my EOS Rebel XS. I can see the thumbnails, but as soon as I attempt any edit, the image preview just goes to a black screen with a question mark.

Any tips?

Thanks. 

[StanNH]

I have not been able to get DPP to directly import images from Photos.  I usually export them to a desktop folder and import from there.  It's also possible to drag an image to DPP from Photos.  It does not seem to be recognized as an extension in the Photos editor, so you can't open it through the editor either.