This:
That thumbnail/out-of-camera jpeg is the raw file, processed by manufacturer’s proprietary algorithms.
So naturally, what you see by default in any non-manufacturer-provided software does not and will not match the jpeg.
The hard truth is, either be happy with jpeg’s and forget about raws; or forget that the camera can produce anything other than raws.
See also, Reverse engineering the in camera development, anyone? - #2 by LebedevRI