Hi djnicholasc.

What version of ITCH are you using?
Have you got Beatgrids enabled (in the Setup Screen)?

If you are using Beat Sync rather than Auto-tempo, then the physical pitch sliders ill change the master tempo when they sweep past the pitch amount in the software and 'pick up' the pitch control.

ie. the synced track has a physical slider location of -2, and the track playing on that deck says that the track is playing at +3, then you would need to move this slider to +3, at which point this slider will now control the master tempo/