I have changed the filter three times in this, and to reset the counter was by pressing the %filter button. Perhaps try holding it for longer - 5 or 10 seconds?

Edit: I had cleaned the wire before the machine asked me to (red light on the screen).

As soon as the light appeared, the reset function worked by pressing the %filter button for 3 seconds.

=> Be patient....

Thanks to Artisticlcabus36.