I also had a stay post with only 2 of the 3 nights. My JW Marriott Venice, post 10 days after check out with only 2 of the 3 nights posting originally. I checked in around 3 pm on the 7th and out around noon on 10th. After lodging a complaint, once again, I received the credit of all three nights a week later.

Every single legacy SPG stay, 3 x Westins, 1 Lux Collection, 1 Sheraton, 1 St Regis have all posted correctly the day after check out.
Every single legacy Marriott has taken at least 10 days to post, one is currently at 12 days, and there have been errors in half of them that's had to have a case filed