There are filters and toggles which allow viewers to limit the amount of data so the map's detail is easier to see.
Adjusting one or more of these filters and toggles with the steps in this link will allow all data to be visible: Tracks Not Showing in MapShare or Garmin Explore Website
If you still do not see the items from your library after checking how the filters and toggles are set, you're probably running into the issue where the library loads very slowly or not at all. This has been going on for a couple of months now, with no significant improvements in performance.