Saw a tech blog post that said Hulu's app sometimes logs you out after an update. It has to do with how the app stores your login info on the device. They said to try deleting the app and reinstalling it, which fixes it for some people.
Crashed on me too last week during a One Piece episode, right as Luffy was about to do something huge. I ended up just sitting there staring at my own reflection in the black screen for like five minutes before giving up. Switched over to a pirate site on my laptop and honestly it ran smoother than Crunchyroll ever does. Have you tried using the website version instead of the app on a fire stick or something?