The reliability of Rewards Mall seems very shaky.

When you complete a purchase, it won't confirm that you earned your points.

If you contact MR and ask, you eventually get the answer, "I'm sorry that purchases made through the Rewards Mall don't confirm that your earn your points. You will just have to monitor your account and see if the credit posts within 60 days."

When things do post, you find out that the description doesn't give you a way of figuring out which posting belongs to which purchase.

This is a variant of the missing stay problem. I'm not sure what it is, but Marriott Rewards seems stuck on inventing and/or participating in systems that aren't 99.99% reliable from the get-go.