I believe this is a limitation of the software right now, and would recommend you contact Zebra tech support to log it as a potential bug. It doesn't mean you can't use it though. I'm not sure what your use case is, but if you are trying to create a template to be used elsewhere, be reassured, the printer can handle a large amount of data in the barcode. If your use case is to have a template that you can add to your application with variable data, then the extracted prn file will get you the template, and you can add as much data as you want when you are sending the print jobs from your application.
Let me know if this answers your question,