In MacOS when an app is in the doc there often is a contextual menu list of recently opened documents, from which one can be selected to open the app with. LibreOffice does have such a list. Unfortunately, it looks like the list contains every single document that has ever been opened (up to presumably some maximum.) That list should be cleared whenever the "recent documents" list in the LO File menu or "recent files" in the start center is cleared.
*** This bug has been marked as a duplicate of bug 115926 ***