I am trying to add shows to my watchlist, but the page is not updated when I add them, and some appear some time later, while others never do. I have tried signing out and in, removing the flag and setting it again, to no avail.
For example, this is my current watchlist:
However, those are not the only videos I have tagged. I am not sure if that is something about those series in particular or a more general issue, since some are added without problem.