This now happens more often than not, almost every time I press the increment progress button the app will momentarily become unresponsive and a loading beachball will appear. Sometimes this also results in chapter progress not being updated, but I believe that may be a different issue as that...
I just looked around and sure enough, it was changed to MyAnimeList. I'm really sorry I didn't even consider that it would be the culprit. I don't know why it would have changed since I haven't done anything with the app or my account, perhaps it happened with the most recent update.
Logging in/out does not fix the issue. Anilist website is up and running and is functioning as normal so I'm assuming it's the API not being able to fetch data. Using the anilist js API in discord works, so I'm not sure what the issue might be on your end.