I remember that the only time i had this, the profile was corrupt. Check the filesize, mine was totally off. If everything seems normal you should try to upload the rig to the rig exchange as private and download it again.
Same here. I had that once and it was a corrupt profile. I found that after I removed one profile after the other from the shared folder (I was only importing 6 profiles, so no big deal) and after I removed one specific profile, everything worked well.