Head coach Matt Eberflus said Thursday that Scales is sidelined with a back injury, Jason Lieser of the Chicago Sun-Times reports.
Scales has missed several days of practice due to the back issue, but Eberflus noted that the long snapper is "on track" to play in Saturday's preseason opener against the Bills. If Scales cannot suit up, Cameron Lyons is slated to fill in as the long snapper for the exhibition matchup.