I haven't used the latest Dining Reservation system, but I noticed that when I logged onto MS and then linked to the dining reservation system, that I was logged on to that system too. It said Welcome Denise in the upper right corner on the Dining Reservation page. However, when I went to the Dining reservation page direct on the WDW website it did not show me a logged in.
Does this make sense? I'd be interested to know if it works for you.