Description of your request or bug report: I’m currently watching Ranma 1/2, which is in manual episode mode, for the moment. I tried opening the Data Manager, and it results in an entirely blank screen (only the site header and footer are accessible).
Not sure what the intended behavior is, but figured I’d note it here.
Trello link:
I ran into the same issue with これはゾンビですか？. The solution was to set it to wish list, then back to watching. I had to re-add the episodes that I had already watched, but it did solve the problem.
Ok! I think this should be all fixed up. The issue was that some episodes had no dates associated with them at all, which should never happen.
I have processes now to double check and resolve those if they come up 
I ran into this issue again with ふたりはプリキュア Max Heart | L22.
I also found a way to reproduce the issue. If I go to the show on two separate devices and update the same episodes to watched on both, then it will cause the problem. This isn’t how I was running into the issue originally, but it appears to be a reliable way to reproduce it.
I can also consistently fix the issue by setting the problem episodes to unwatched and back to watched again.
