Problem is back again - can’t check movie, unable to remove watchlist. Not working in v2 or v3. Have also had the same problem on my phone. Okay, I notice the last time I reported this is was also the same hour (only 8pm on the west coast of North America), so something is going on at this time of the day.
edit: I never got the changes to stick before closing the window and putting the computer to sleep for about an hour BUT I just opened that movie page again and both the watchlist designation was clear and the movie checked, so it seems that the request makes it to the server but the response doesn’t make back? That’s all I can come up with.