Found the solution. If you "Objects" - "Display Name Settings" turned off, the Blade of Light is not visible. Turning this off in game to remove the vast amount of noise from object titles, such as "Entrance", renders the marker in this fight unfinishable. Can this please be changed to not an Object Display Name, or at least provide a more graphical solution for those of us who prefer not to have the names of every little thing written out?