loading hard disk on the Raspberry

Hard disk on the raspberry’s usb (3B+ but idem 4) with separate power supply loaded with half, volume even with a rescan or update only takes half the music on the hard disk, if you let it turn on all night it takes all. Not very cool when you add music to the hard drive. For six years of volume I have never had this problem. New version 2.657???
Does anyone have this problem, thank you.