I've now stayed at 3 Marriott hotels (all legacy Marriott) since the merger. At two of them, I've asked the FDC's what they show my status as. In both cases, they told me that they see me as "Platinum Premier" -- with no mention of Ambassador. When I log into my Marriott site, I show LTPP as well as current-year PPE+A. In my current hotel, where I've stayed most of my nights this year, I pressed a little bit more, as I know the FDC here. Still no recognition of Ambassador status.
One of these days.....
-mvitale