Question by Nino:
If you choose RAW alone or RAW and a smaller JPEG the RAW the file is not full resolution. It is 4896 x 2760. It should be 4896 x 3264. To get the full sized RAW capture you need to choose RAW+(full sized) JPEG. Am I missing something?

Solution by Ryan Williams:
I recall reading that Lightroom (and probably ACR) automatically crops RAWs to 16:9, so you need to go to the crop tool and remove/change the crop. This may only apply to when RAWs are saved in a certain ways though, as you describe.
 
Nino´s response:
That seems to be exactly what is going on. For conditions I noted at the start of this thread the RAW image opens in ACR cropped to 16:9. You do have to click the crop tool then the crop shows. Hit “esc” and all is fine

See discussion on forums.dpreview.com