In PLAXIS MoDeTo CONNECT Edition V20 (release of January 2020), the Save Selection and Save All options generate an empty .TSV file when used with rotational soil reaction curves (moment-rotation and base moment-base rotation).
This is now fixed in PLAXIS MoDeTo CONNECT Edition V20 Update 2
Workaround for older versions: Choose ‘Copy Selection’ or ‘Copy All’ and then paste the table data to its destination. A TSV file can be created with any plain text editor