I clicked on the number and it toggles on and off but it seems like the track is still selected and with the number toggled off, bounce to track still gives the error.  No matter where I click to the right of the number, it stays selected.  In fact no matter where I click on the screen (even below the tracks), it stays selected.

I either use the ctrl/shift A or as I said I can click on the space below all the active tracks ( blank )  where none have been created yet and that un selects any highlighted tracks.
 
In 8.5 you could also use the EDIT menu and choose "selct none" off the top of my head I'm not sure if that's gone now  with the "new" software.