EXIF data missing from 6D

:-(. Just taking my firsts shots with new 6D.  So far I'm just shooting large, high resolution JPEGs, no RAW.  When I import to Mac Aperture, about half the images have no EXIF data.  Unknown camera, unknown lens, and unknown ISO and shooting parameters.  Half the images show full EXIF images.  I haven't seen a pattern yet.  Anyone else notice this or an idea as to why it s occurring?

thanks,

Jim

Boulder