Just writing on top of this existing thread as my concern matches the title.
I managed to get back to DM recently after being dropped to GO about 8 months ago. My app still says "Your upgrade to Diamond membership is in progress" for about 3 days now. So how long does it usually take?
I never consciously tracked it in the past but I'm asking as I have a flight tonight and obviously want the DM benefits for that flight. Thanks.