Rest assured, the movies are being tracked properly and being added to your account, this is simply a display bug.
There are two separate issues that could be related to this bug:
- The "strip" of movies on your profile page (also known as the "Movie Carousel") may or may not display your most recently watched movies on the Movie Carousel
- In addition to issue # 1 above, a recently tracked movie may not appear correctly when you open the "Movies" section.
- They may appear out of order, or not appear at all