Contact Sheet Fail

I was using Adobe Bridge to generate a 4x5 Contact Sheet of 160 images. This message appeared. 

Apparently it processed the contact sheet successfully with image that ARE supported. Yet I am left to wonder which images WERE NOT supported. Some. Since it did not indicate which files were not supported, nor which file types are supported, I had to manually reconcile the output.

Please indicate, of the selected files, which were not supported image files.