Not sure what bearing multi-point calibration may have on a digital code written into a register. Why would measuring a frequency-independent resistor connected between Vout and Vin (voltage sourse and virtual ground) within 20Hz frequency span require multi-point calibration?
Thanks for providing the links to new software. Old version works just fine and provides necessary functionality - there seems to be no reason switching to new version and editing the code.
I think it is quite black and white - AD5933 works as advertised when number of settling cycles is set to 1 and it does not when it is set to 0. Wthout looking into some relevant documentation one can hypothesize endlessly as to what is causing it . Is there a chance you could share this information?
Have a great weekend,
Snorlax