DJI said they are well aware and offer privately the Fix. Here I publically show how it's done. FOllow the steps for your Mimo App to correctly now load your footage correctly  to the camera.
this video is the Fix till DJI can figure out why

followed your steps to the letter: deleted & reloaded Mimo. Registered, gave all permissions and took a short video using mimo app video thumbnails showed up but they still don't play

multiple times: same issue

Yep got to live with it, simply just put off  the airplane and or wifi and use the app then back on again, quite annoying, some one is not happy with some one that sounds LIke DJI to me