I believe the tuner is married to the vehicle.
If it wasn't purchased/registered to the vehicle it may not access the PCM to load the tune.
There should be nothing stopping the dealer from reflashing the PCM.
Are you sure the previous owner didn't remove the ProCal and return to stock?
Finally, the SCT tuner will read codes on any obd II vehicle, at least through 2017.
It will read codes on Chevy's and Subaru's (both my other vehicles).
Where did you get the tuner?
2013 BBK Short tube, E-Force Stage 2, M/T 275/15/60 DR's, BMR LCA's with lowering brackets, Alum D/S, Strange FRT adjustable struts, strange adj rear, whiteline pan hard