This problem was annoying me for a while. I finally fixed it.

 

 

 

Go to your inbox, then on the top menu bar, click “Folders”, then click IMAP folders. Then a dialogue box should pop up. Then untick the bottom box that says “when displaying hierarchy in outlook only display show subscribed folders”

 

Your inbox should then appear. Why Microsoft, why oh why did you make it so that you can’t even see your inbox by default? What were they thinking…