Some Android phones drop the yaw signal from FPV radios over USB. The reason: the original USB joystick standard only defined three axes (X, Y, Z) — back then, joysticks didn't need a separate rotation axis. Yaw on modern radios uses a newer axis called "Rz" (rotation around Z), and Android's input system filters it out unless the device matches an Xbox-style gamepad layout, which FPV radios don't.