DIAGNOSIS The label margin or offset settings in your printing software are incorrect. The printer aligns to the software's commanded start position.
FIX You must calibrate the sensor and set the offset. First, perform a sensor calibration. With the printer on and lid closed, press and hold the FEED button for 5 seconds until the LEDs flash. It will feed one label. Then, in your app (e.g., ShipStation, Pirate Ship, Easyship), navigate to printer settings. Find 'Label Offset', 'Horizontal Adjust', or 'Media Position'. Increase the value in +0.5mm increments. Print a test label after each adjustment until the content is centered.
IF THAT DIDN'T WORK You have selected the wrong label template size in your software. Verify you are using a driver template for '4x6' (101.6mm x 152.4mm), not '4x5' or 'A6'.
HEADS UP The physical alignment of the label roll on the spindle does not affect print positioning. Do not attempt to mechanically adjust the printer.