Wheel bearing with assist parking / without assist parking?

I needed to replace my passenger rear wheel bearing hub assembly along with some axel parts. The shop showed me the parts from their written quote. I asked if they allowed bringing in their own parts and they said yes. I asked if the part numbers on the quote were exactly what I was needing, and they confirmed. Once they replaced everything my ABS and traction light came on along with a notice stating, "hill start not available" (or something like that".... after 2 trips back to look at with failed diagnostic attempts he stated that it was because I bought the assembly with assist when it should have been without (even though that's the info the quote had, but anyways) does that issue have anything to do with the sensor of the wheel bearing reading/giving out the "assist"... like could I just by a new sensor for it and replace only that?