ERG mode not working on Flux S


Have a brand new Flux S and erg mode is not working properly on it. eg... if i set resistance for 150 watts, and i pedal very slow cadence, the trainer will increase resistance so that my watts are at 150... however if i speed up and get my watts up to say 250 or 300 and hold steady, the trainer does not back off the resistance to bring the watts back to 150.

Firmware is fully up to date. Any ideas?

Ive also tried this in the small ring at the front and half way down the cassette which is something ive been reading and still makes no difference. Feels to me like the trainer is faulty.... Any thoughts?