Never say Never..
Good tracking programs are actually able to flip-over..
Which means that with an 90° overhead pass you will have EL >90° ... <180° flip over...
This is important with LEO satellites, in particular when you need to rotate AZ by 360° depending on where your Rotator Stop is (either Noth or Sourth)..
If you have done the 180° calibration correctly, the 90° should be OK too.
Again.. you have to mechanically bring it into 180° and make sure the antenna is horizontal aligned and only than you adjust the Potentiometer FULL SCALE ADJUSTMENT. And yes, the mechanical stop of the rotator is slightly more than 180°.. So you have to go in front of your house and check with your eyes if it's 180° or not