The first Step is access to the Ordering Dashboard, and open the store with the GPRS problem.
Now, open the "Notifications & Payments" menu, and click in the "Clear GPRS stuck order" option.
A pop-up will be open, here, if You wanna clear all the orders in queue, you must check the "Clear all order files" option or uncheck if you wanna remove only the latest stuck file.
And now! please make a test with the GPRS Printer again.
Glad we can help.