I believe there is an issue in SGP that if dither is unchecked but "Settle at" is specified that SGP will still command a dither. Or it could be that if any autoguider is selected that SGP will command a dither (effectively ignoring the "Dither" option). I can't recall which, but there is an issue with one of those that will command a dither when you don't expect it. If you really don't want to dither then just select "No Auto Guider" for the time being.
Thanks,
Jared