well tell me this.
Try downloading from your gallery a regular image already processed that is not showing exif that you sure had exif. Reupload the image is exif extracted?
Next upload a regular image that has exif from your camera etc that is new is exif extracted?
Your answers to these questions will let me know how to answer.
Basically if new images are being extracted exif fine but old ones cant then it tells me that the header data has been stripped.