There is a bug with cr6.7 with cropping of 5dm3 images.
Set the 5dm3 to include cropping data in camera (like 4x5 crop) so that you see the image on the back of the camera with the crop lines.
Open the raw file in cr6.7 and you cannot change the crop outside the area that was set by the ratio in the camera.
In canon DPP you can reset the crop and get back the parts of the image that has been cropped off with the camera setting, so the data is there but cr6.7 will not allow you to recover it.
Image while cropping in cr6.7 (only the 4x5 crop set in the camera)
image while cropping in Canon Digital Photo Pro (notice the extra image at the sides)
Retrieving data ...