QRotationReading bad angles

Hello, i'm testing QRotationSensor on my Ulefone Armor 3WT and i don't understand why it's returning strange values from -57° to +57° instead of -180° to 180 like the documention say. It's not the only problem. I have made a little video about one minute to show the differents angles when moving my phone : Video

I don't know if it's me, my phone or Qt, but one thing is sure... It doesn't work .

If you want to test my project i give you a google link : TheLink

Thanks for your work guys, Qt is so cool