In Bookmark Manager a bookmark’s URL only appears when the bookmark is actually selected.
Otherwise you don’t see the URL.
Given the ease with which duplicate (triplicate, etc.) bookmarks can end up in Bookmarks, I suggest that Bookmark Manager always display the URL of all bookmarks currently displayed on-screen. Aside from other benefits, that would make deletion of duplicates, etc. quick and easy.
Here is how bookmarks would look if TOR’s (i.e., the TOR browser’s) implementation were copied: