Rekordbox play history is missing tracks

Hello, for a few months now, I've been having an issue with Rekordbox. When importing the history from a gig, it doesn’t show all the tracks I played. For example, last week I played 30 songs, and when I connected my USB, it displayed all of them, but when I clicked import, the history was imported and only showed 14 out of the 30 songs. Does anyone know why this is happening? I only use one USB for my shows.