RAW+JPEG captured, but only seeing JPEG

I recently shot images in RAW+JPEG on my Canon Rebel XSi and imported the images into my Photos Library. I have my Preferences set to Copy Items to the Photos Library and my iCloud Preferences set to Download Originals to this Mac. For some reason I am not able to use the RAW as the original. In fact, when I go to these images in the Photos Library, I don't even see the RAW file. I only see the JPEG. I can see the small "J" in the white box overlapping another white box in the Photos display window, so I know there must be a JPEG and RAW version, but when I go to Image menu, the Use RAW as Original option is grayed out. I am using the latest version of OSX and Photos for Mac, so I don't understand why I can't access the RAW file. Perhaps it has something to do with the camera firmware? I don't know and have never had this issue before when using Aperture, so I am curious as to what might be causing this problem.