After creating a barcode in ArtPro and setting the fill color of that barcode to transparent using the predefined keyboard shortcut, the barcode cannot be edited anymore after saving, closing and reopening the ArtPro file.
After performing the actions described above, the barcode can no longer be edited (user cannot make any changes to the barcode via the Barcode window in ArtPro).
Using the Barcode window will only result in a new barcode being created.
A solution to this very specific problem is currently not available. A permanent fix is arriving with ArtPro 14.
When setting the fill color of the barcode to transparent, use the Window > Paint menu instead of the keyboard shortcut.