Command line PDF generation (not using -convert-to pdf)

[hindmost]

I am attempting to set up a method to automatically generate pdfs from xls files.
Note I am not using the -convert-to pdf option because many of the spreadsheets have hidden rows but for some reason are added to the pdf anyway.

I have installed the Cups-PDF printer and printing to this printer works fine when I open the files using the full OpenOffice GUI.
However, when I attempt to print the same document from the command line:

soffice -pt Cups-PDF /convert/spreadsheet.xls

Nothing happens, no error but also no pdf is generated. I have tried converting spreadsheet.xls to a .ods file and running the command against that but it also does not work. The command line does work however when it is ran against an extremely simple ods file but not against the same file saved as .xls.

What I would like to know is if I should look into using the various programing API's to automate this conversion process. The conversion certainly works when it is done through the GUI. I have tried this with LibreOffice and it behaves the same.

Thanks for any ideas.