Not sure if you would call this a bug or as designed. If you set the Visitor tabs location to be Top bar but don't enable the top bar all the links disappear until you turn on the top bar or move the visitor tabs back.
We can put some notes on it more but it's kind of as expected. It's like editing the footer contents but not enabling it. It would get messy to check all the locations and their respected properties -> Logo inside nav, top bar ect
