I have been having this problem for a very long time (ever since the redesign of the website), but it's only now that I finally found the root of this issue - the translation. In the Czech translation of the website, the buttons "Add to list", "Mark as Favorite", "Add to your watchlist" and "Rate" in the movie profile are inactive. Nothing happens if you hover over them, so one cannot rate Movies/TV Shows.

It works neither on mobile nor on the desktop. It works fine in all other translations I have tried (English, Spanish, German, French, Slovak), so that could be the reason why no one has noticed this problem yet.