You could try removing all the libreoffice settings for the misbehaving user. Try this command to rename the folder with all the settings in it:
and then start libreoffice again.
mv .config/libreoffice .config/libreoffice-old
If it starts then it's something in the settings that is causing the problem. You might as well delete the bad settings folder and just reconfigure from scratch:
If it still won't start, then I'm out of ideas and you may as well put the settings folder back:
rm -rf .config/libreoffice-old
mv .config/libreoffice-old .config/libreoffice