Bug: First track gone when i "Backup project"

How it happens:

(I use Macbook Pro and iMac)

  • Take existing project and make backup through Back-up project onto external USB hard-drive
  • Tick off remove unused files
  • Transfer is ok
  • Open project from external hard-drive on another mac (or from the machine when it’s transferred from the eHDD)
  • First audiotrack is either missing or incomplete (if not missing, audio usually cuts after approx. 10 seconds)

    I’m trying to work on my exam and do a mix of a song, but without the bassdrum it’s sort of pointless really. Please look in to this, i have no idea what causes it or why! I have tried this on two different projects and it happens every time.