Hundreds of songs missing from Smart Playlist

I have created a smart playlist that includes the following rules: Genre contains Pop, Genre contains Ballad - Pop, rating is greater than 3 stars. I recently noticed that there are a lot of songs that fit this criteria, but are not in the playlist. I have checked the songs included to see what might be different and there is nothing. The information is exactly the same. I even deleted the list and created a new list which yielded the same result. The main reason I'm so meticulous about classifying all my songs is so that I can use this feature, so this is very frustrating.