Letterboxd.com (I don't need more characters)

When liking a movie, on letterboxd.com, Brave doesn’t change to ‘liked’. After hitting ‘like’, and re-loading the movie’s page, Brave shows the movie without the ‘like’ button orange coloured.
Extensions and ‘trackers & ads blocking’ disabled.
When liking a letterboxd movie with Vivaldi, the movie page changes to ‘liked’. And after re-loading the movie’s page, Vivaldi shows the movie with the ‘like’ button orange coloured.

The same goes for unliking a movie. Not just on a movie’s page, also all liked movies in my account. Meaning, the page that shows all the movie’s I have liked. With Vivaldi I’m able to unlike any movie, with Brave I’m not.