Please, could you clarify what type of printer is printing correctly.
My suggestion would be that you verify if the printer is correctly configured. You can verity it with our Zebra Setup Utilities tools. Please, go to the following link, and download the apps (desktop app & the Android app). Send the same ZPL code through the open communication port and check it. These utilities apps would help you to verify what is happening with your printer.
If after the tests done you still have a technical issue affecting your printer, you will need to open a case with our Technical support team on the link below.