MDE is having some major issues right now. I lost the ability to see my tickets on the desktop, and on the app I basically lost everything: resort reservations, FP+, and dining reservations.
This is the response I got on chat support this morning, bolding is mine:
"We apologize, unfortunately at this time, our system is still going through a magical enhancement that is affecting Guests’ ability to see previously linked tickets, make FastPass+ selections and see correct Family and Friends list information. We currently have not been notified of a resolution time. I would suggest that you come back later today or contact our Internet Help Desk, they can verify any itinerary information for you or assist you with attempting to make any FastPass+ selections."