Can't change aperture on Mavic 2 pro

Hi,

I try to set manually the aperture on the Mavic 2 pro

I can see the aperture change to 2.8 if I select "Auto" but if I change the mode to "manual" -M I can't change it?

why? I see the Mavic 2 pro support on other apertures 

(F_2_DOT_8, F_3_DOT_2, F_3_DOT_5, F_4, F_4_DOT_5, F_5, F_5_DOT_6, F_6_DOT_3, F_7_DOT_1, F_8, F_9, F_10, F_11)