I use the same equipment. If you think about the way the SItech II controller works with the popup window, by default it counts down in seconds (unles you’ve changed it), does an offset init by default then closes the window. So if you intervene manually in this process, you need to click offset init and OK (need both) otherwise you are not refining your pointing accuracy each time a plate solve succeeds.
I follow the process I described above (using Platesolve 2) and it works fine. I image at F8 with a celestron C11 and Sbig STT8300, which gives a detailed image scale for galaxy imaging. I ask SGP to iterate until it gets to within 90 pixels and it does this fine in two iterations.
I just think 90 pixels is fine when you think about how many pixels there are on your computer monitor, and this avoids unecessary iterations too, which all take time (and risk failure to solve).