I believe there is a bug currently with importing .msf setlist files. I will get it fixed for the next update. Having said that, what you are trying to do isn't currently supported with .msf files. I'm going to be adding a new option for sharing setlists that exports only the song list so that another user with the exact same songs in their library can update their matching setlist. This will be a .mss file (MobileSheets Setlist) to distinguish it from the .msf file which contains all song data and files in addition to the setlist.
Mike
Mike