All tracks on Bandcamp need to be part of an album. Any loose tracks that don't belong to an album can't be matched to your music from other platforms, so they won't be added to your Supertape inventory.
All of your albums should have UPCs and tracks should have ISRCs. This allows us to match your music to other platforms far more accurately.
Albums from other Bandcamp profiles can't be imported. Either add the album to your Bandcamp, or in the case of labels, request that they add you.