Sodaq One and HX711 load cell amplifier

I am porting code from Autonomo to SodaqOne. There seems to be some difference in the two boards behaviour?

The Sparkfun HX711 load cell amplifier uses Bogde’s library: https://github.com/bogde/HX711.
There is a calibration sketch which tares the scale to zero and then allows changing the calibration factor to give a known weight reading. This works fine on the Autonomo. But with the same code on the Sodaqone, the sketch does not tare back to zero (it gives about 1Kg). Any ideas why this might be?