Ok I figured it out. First of all, I had exported the package to a newly formatted drive, before I ever connected the drive to the Shield.
Then, I exported the package in a root directory on the drive I had called "Launchbox". If you put the files in this kind of file structure, they won't be recognized.
What I did is I moved them to a new folder "Android" on the external drive and used the following path:
Android>data>com.unbrokensoftware.launchbox>files>LaunchBox
Now, everything is recognized fine.
Thanks for the help!
P.S. Your tip helped me figure it out. I looked at the internal drive and saw the file structure where the Launchbox folder had been placed. Then I saw the Shield had created a similar file structure on the external drive (Android>data> etc...) and figured that must be where the files had to go.