Changing your label type and size are the main causes for the printer skipping labels or continuously feeding.
Printer hasn't learned your label. Please try the following steps to solve these problems.
Re-run the automatic label identification.
①Disconnect the USB cable from your printer, then simply press and hold the Feed Button for 3 sec.
②Printer will move the label back and forth to determine the gap size and other properties of your label.
③When the label is at the tear off point; re-connect the USB cable to the printer and resume printing.
Check the video " Automatic identification"
If your operating system is sending a longer / shorter label to the printer. You need to change the label size.
Select or input label width and height that matches label size installed in printer in prompt window.
Open "Devices and Printers" -> right click on "Label Printer" -> choose "Printer Preferences"
You can choose the size you need in "Paper Name". If the size you need is not listed, then click "New" to create needed size (input the size of "Paper Width", "Paper Length"and"Paper Name", then click"Ok" to archive.).
The application you are using (e.g. Adobe Reader) could be over-riding your driver label setting and sending the print in a larger / smaller size to the printer. Look for"Page Setup" or"Paper Size" in the print prompt and ensure it is set to the size you want.