Hi all,
sorry for the delay, I've found that exporting the gCode from the "full settings" of Cura, in the gcode file there isn't the MTYPE line, so the selected material is used and no alert appears. While, exporting from the "quickprint" Cura's settings, the gcode has the MTYPE line.
So now everything is ok, probably I did a bit of confusion between settings and material selection...