navigation button missing on desktop editing but shows on mobile editing

Navigation button missing on desktop editing but shows on mobile editing.  Some time ago a button went missing on my desktop navigation bar.  I could not figure it out so I made the best of it and edited the remaining buttons to work.  Tonight I was on the mobile version and the button is there?  I poked around in there a bit but was unable to figure it out.  The page is NASCAR.  There should be a total of 6 buttons in the navigation.  Any help you could provide would be great.  Thanks