On my ubuntu Linux system I used to get a plain white icon for the main thumbnails screen from which I launched Libre office individual programs. Now that page only appears after I have used one of the individual Libre Office programs and then saved a file. I don’t know if I have inadvertantly changed a setting but cannot find anything in the options to correct this
Try launching as soffice.
after a recent auto update from libreoffice the missing icon miraculously reappeared without any action by me. So the matter is resolved for the time being.