Same problem here. My solution was to send a message via chat to Marriott’s customer asking them to notify Marriott IT that push notifications weren’t going out on Chat and guests are not receiving the messages. I told them the problem was at multiple hotels, not just them. I went to my dinner reservation at the wrong time last night because of this.

Response:

“Good morning, our sincere apologies for the inconvenience. Thanks you for the feedback. We will inform our IT department accordingly to check on this issue as soon as possible.”