I use a RoboFocus with SGP without any problems - so the hardware should not be a problem.
If this is a new set up, I would suggest having the focuser all the way in to start with. Move it out (maybe one 10th of the total travel) and take a ‘Frame & Focus’ shot. (Could be a 5 second image at Bin2). Most likely you are way out of focus. Keep doing the same with gradually moving the focuser out, until some point that you can say…“the actual focus point is in this vicinity”. (If you have a Bathinov focus mask, then of course you can get to the spot much more quickly). In any case, only when you are near focus, does SGP autofocus routine do its job, and once you are in the ‘ball park’ of the focus point, then you can adjust the steps to get a better curve.
If for some reason, it is not working at all - then you must check you are sure that the back-focus distance to the chip is still OK with the new focuser and whatever connections you have in the image train.
Just my initial thoughts…