OK, so I clicked on the "register now" link for the 50K promo, which took me to a "congratulations, you're registered" page.

I was expecting them to ask for my MR number, but they didn't. I wasn't logged in either.

I checked my "My Promotions Progress", and it wasn't listed there either.

So I went to another computer in the office, cleared the cache on the browser, emptied cookies, made sure nobody was remembered on marriott.com, and tried clicking the link again... Same result: "you're registered".

The short of this is: even though it's sending you through to the "you're registered" page, it's not taking any personal information for you to have registered. Ipso facto, you're likely NOT registered even though you clicked the link.

I'd keep trying back until they have fixed their error.

YMMV...