Does the pump generate 9 bars of pressure when brewing.
La Cimbali pumps are very sensitive to running without mains water pressure and after a fairly short time running like that - they fail!!
The autofill circuit itself should not be affected by not having water as it uses a float in the boiler which operates a reed relay on the outside of the boiler....
Can you hear the pump motor running at all? When you operate the hot water outlet boiling water is forced out by the pressure in the boiler but this is normally mixed with cold water supplied by the pump.... some of which replenishes the boiler water at the same time .... this is all done with the economiser attached to the boiler.