Black Not Set to 100% K
You ordered single-colour black labels, yet the print file has CMYK colours
Some black elements in your artwork have been created using CMYK values rather than 100% black (C=0, M=0, Y=0, K=100).
Watch the video to learn how to identify black colour values in your artwork, set black elements correctly to K=100%, and understand the differences between standard black, rich black and Double-Hit Black.