I think this may be a Canon problem, not PM:
When shooting RAW+JPG with the 5Dmkii set to AdobeRGB then looking at them in PM with color management ON:
The embedded JPG looks flat and PM reports it as sRGB. The separate JPG looks correct and PM reports it as AdobeRGB.
Turning off color management in PM makes them look the same. So it seems the only problem is that the embedded JPG is intrepreted as sRGB while it really is stored in AdobeRGB. It could be the camera doing this error....or PM....
I tried setting default profile in PM to both sRGB and AdobeRGb but with the same results.
The 5DmkiII is embedding a full size JPG in the RAW, so the RAW+JPG is really not needed, and I want to use only RAW, but then all images look way too flat (looking at the embedded preview). One solution could be to set the camera to sRGB, but I really dont like that....(and have not tried it).
Rgds
PM