Judging from the posts, I guess the North American based Ambassador centers are overwhelmed with the new Ambassador members.
And they might failed to train new ambassadors fast enough to cope with the demand.
Mine, based on Singapore, seems dont have any issue to respond to emails and phone call.
The apps however still show the global toll free hotline instead of ambassador line.
And the email address, I still send the correspondence to both @
marriott com and @
marriot service com (and ambassador service email if the request are urgent ... but none so far. )