Hello Javier,
i've just checked with mine (as i did play around with Spirit
)... the easiest way to see if Esc telemetry is really working is battery voltage ('Volts') in Esc telemetry screen (iX12 in my case, should be same with DX9 iirc). 'mAh used' only under real load (even nothing during bench-run without blades in my case), the same story with current. and 'throttle%' seems to come from Spirit itself (Spirit's throttle out channel, not Esc's throttle in). but battery voltage is a clear indicator... if it does not show you the main bat V => telemetry not working. i've connected Esc telemetry cable on/off and checked....
NB: ... and blades off during bench tests