This is because Mesu 200 has axis encoders with accuracy 2.16 arc minutes.
If you are using encoder settings other than ignore mode, you should set 'until error is less than' on the plate solve tab of SGPro to a value around 2.16'.
If you set the encoder setting to ignore, Sitech uses motor encoders on Mesu 200.
Motor encoders are much more accurate than axis encoders.
SGPro centering routine can get to 2 arc sec accuracy within 2 tries with ignore mode for me.
The accuracy is 1 ~ 2 pixels with 1120mm fl and 4.88 micron pixel camera.
A potential problem of only using motor encoders is pointing inaccuracy if the friction drive slips while slewing.
I've never had slipping problem with rough balancing though.
If you don't need centering accuracy more than 2.16', polite mode is perfectly fine.
You just need to adjust the SGPro setting that I mentioned.
Donghun