I also have an issue in getting some points back. Had to cancel a three-night C&P reservation for Grande Bretagne Athens made under the old SPG program (@ 10,000/night). Post-merger, I should be getting back 30,000 points/night x 3 nights = 90,000 points total.
I have waited a week, and nothing shows up, despite the lady on the phone assuring me that I would see these points back in my account within 24-48 hours of cancellation.
I now might need to cancel another C&P reservation for Excelsior Gallia Milan (would get back 30,000/night x 2 nights), but am hesitant to do so while Marriott still has these technical issues.