Go again to the window where you can see that the photos are marked for printing, check the name of one photo and use it to find the location of all 524 photos. Press the Start menu, type the name of the file in the Search programs and files field, right-click the photo and select Open file location:
After that, import all photos to the application and try to print them. If you can't, use the contact information from the official web page to get in touch with the support team.
Note: If you can't find the name of the photo, go to Start and type modified:date. You should use dd/mm/yy as date format (27/01/15 for example) and to type the date when the files have been transferred. The search engine will list all photos and you can find all photos using the Open file location option.