Official comment
@Luigi > I had a laugh at this one, because not only did I not know which icon you were talking about (I had to look it up), once I was reading the manual, I still wasn't sure what that icon was or where it appeared because I never use the Explorer view of rekordbox! (I typically have mine disabled because I never browse my music through the Explorer.)
As it says in the manual, the icon is to indicate which tracks have been imported and analysed, and will only appear when browsing your files within rekordbox's Explorer view, which you can toggle through the View page of the rekordbox preferences. Once there, find a folder with music, and you'll see any imported files showing with that icon. Any files not imported will have a blank in that column, whereas files with cue points will show as such.
