Garmin Bluetooth sensors, already member, rider does not move

I am already a member via iOS. I have Garmin Bluetooth sensors, batteries are new. Cadence sensors connects, however speed sensor is rarely connected, but then says no signal or even if it doesn’t say that, rider never moves.
I disconnected my iPhone and only use my ipad, so single connection issue is prevented.
My trainer is Btwin inride 500, with no connectivity. Why I cannot solve this issue? Is it faulty sensor or what? Thanks