I tested the assets starter solution on an iPad 3 and scanned a couple bar codes with no problems.
Make sure you are using FileMaker Go 13, scanning is a new feature added to 13.
The iPad and iPhone have different layouts so make sure that you have not accidently changed a setting on the scan button on the iPad layout.
Also, there is a known bug where using Insert From Device to insert a picture into a container field keeps FM GO from successfully scanning a bar code from the same camera (front vs back). So you may need to check for that possibility.