A lot of people are reporting problems with Amex not posting rewards dollars for their OBC cards as quickly as they have in the past. A simple solution is to either call in or start a chat and ask for the rewards to be accelerated. In my experience, the agents were almost always willing and able to help. In the 8 or so times I’ve done this, I’ve only had one agent say it wasn’t possible. However, a subsequent representative the next day was able to fulfill the request.
This is a bit speculation, but I believe you need to have paid your account for an agent to be able to accelerate your rewards.
A lot of people might not want to do this for fear of drawing undue attention to their [MS-heavy] accounts, but it’s always a good option to have if you need it for whatever reason.