ERG mode Issues Zwift Hub One

Just returned to using zwift now the weather is so bad.
I jumped into the 20-40 workout to get me started and I just cannot acheive the asked for power.
Previously if i pedalled slowly the zwift hub would compensate by getting harder, now it gets to a certain resistance and then its up to me to pedal at a crazy cadence, im lucky to acheive a gold star let alone keep it going for 20 seconds. I gather theres no manual calibration option now so what can i do?