Comment 33 for bug 1672139

Only other workaround that I'm aware of to find the parent folder of a bookmark from the search results is to change the browser to Offline mode (Alt > File > Work Offline) and then open up the bookmark in question. Once the bookmark is open, you can click the Star icon in the address bar to edit the bookmark and see what folder it's in.

Kind of clunky but works in a pinch :\

I sure wish this was natively built into the browser.