thank you this fixed the issue for me!
You have to exit the app rather than going the Home button on the Roku controller. Hit the back arrow button on the Roku controller. You'll be prompted with "Are you sure you want to exit?". Select "Yes".
Then when you log back in the thumbnails will be viewable again.
I had the same issue. At least for me, I found exiting the app instead of hitting the home button would solve the problem.
Hit the back arrow until you're prompted with "Are you sure you want to exit?". Select "Yes". Now when you relaunch the application, the thumbnails should be back.
Good news! MagellanTV reached out to me last week. They have done a core-up rebuild of their app and, from what I have seen, it appears to be running just fine. Deinstall and reinstall and I didn't even have to log back in. Thanks, MagellanTV, for your effort!
The screen kept showing black on my app whenever I tried to watch a documentary. It might be irrelavent to Roku as I have an android tv, but maybe restore display settings to default on your tv? I had a problem with youtube for a long time where the picture would turn grey.... I discovered this and decided to try it when getting black screen on MagellanTV, and it worked!!! Not sure why I have to do this, I thought this was just a problem with my TV...