You can now upload Passbook® pass thumbnail images via CSV. Just create a column for the thumbnail images and populate it with links to the images associated with the pass holders. Skycore will then pull the images from the links, resize them and insert them in the pass file. You still have to make sure that the links lead to a PNG file type. Skycore will resize the thumbnail for insertion into the Pass.
Before you were only able to populate the text fields via CSV. Now you can use a CSV to populate all fields without the bother of populating part of the pass with CSV and then editing the thumbnail field through other means.
The Passbook CSV data import interface showing the column with image URL being labeled