I imported a folder of photos in Canon CR2 and DNG raw format into Photos.app. They show up fine locally in the app (I can edit them), but they don't upload to iCloud. Ordinary JPG files in the same folder upload successfully. The RAW images were shot without corresponding JPGs, ie the CR2 and DNG images are the only copy.
Are CR2/DNG unsupported by iCloud, or is there something wrong with my setup?