My experience - I had booked a cruise, and it worked fine.. I was like wow, not sure why everyone is having a hard time. Then I had to cancel that cruise and rebook it under a different booking number to get some FCCs applied. This is where the nightmare started.
The App only shows the old cruise. Won't let me link the new cruise, won't let me log onto the cruise just using my booking number.. I've deleted it a few times. However, on the website, they have a link where you can use the web version of the medallion app, which worked just fine. I was able to get into the cruise, it had all my information, and now shows me that I am in the Green lane. Still can't get this same information on the AP.
After I deleted it and reinstalled it a few times, I noticed it is now showing me cruises I canceled weeks ago. Read somewhere in here that someone asked them i their grandkids could help, I would have replied they obviously used their grandkids to write the app
They have a phone number listed to call under delete account on the phone app. Going to try to call them and see if they can fix this mess. Not really caring that much as it let me order my medallion and I got a confirmation email, and will most likely not use the app on the ship unless I absolutely have to. Hopefully by then it will have cleaned itself up.