When the printer doesn't accept a label was printed correctly, it will attempt to re-print it.
Try the following steps to re-run "Automatic label identification" so printer can determine the label size.
①Turn power switch off . This clears any pending print jobs.
②Load your label.
③Press and hold the Feed Button while turn the power ON, until you hear two short beeps and red light flashing one times, then release the Feed Button. Printer will determine the gap size and other properties of your label.
④After the determine, it should resume printing.
Check the video "Automatic label identification"