Documents appear correct scale on screen in text editor. Printer settings are correct. But paper and pdf prints are reduced to about 65% size and left-justified on the page.
The problem occurs if the setting in the dialog box at
Tools / Options / LibreOffice Writer / Print
has the option for ‘Comments’ set to ‘In margins’.
The option needs to be set to ‘None’ in order to print at the scale chosen for your printer.
Unfortunately this setting seems to be saved in some obscure place in User Profiles
and you may have to change to the correct ‘None’ setting in every new document you create.