Try the following:
Choose another default paper size for your physical printer. For Dymo large address labels, the size 99012 Large Address works well.
In Provet ProPrint (macOS) settings (for one-click printing), set the paper width and height the wrong way around (height value in the width field and width value in the height field).
If the previous steps do not help, contact Provet support and describe the issue in detail. When reporting issues, including images helps Provet support in solving the issue (see examples below).