Sort by Ratings Not Working Properly

I am using iTunes for Mac, version 12.3.0.44. I rate the favorite songs in my library with 3 to 5 stars, and sometimes sort songs that way when looking for favorites. The sorting has always worked fine until today. Now, I still get the 5 stars before the 4 stars, etc, but there are many songs with the stars greyed out. These songs have no stars assigned to them by me, but show up amidst all the ones that do. Any idea how to fix this?