Sensors do not work simultaneously with iPhone 5S and runtastic Mountainbike app

Unfortunately, the sensors do not work at the same time if you use an iPhone 5S with the runtastic Mountainbike app.
It's either the speed or cadence sensor. But never both simultaneously.
This makes the purchase of both sensors currently relatively meaningless.

Has also recommended to the App iBiker the Polar to test it is not working.

I stand with the Polar Customer contact and hope to have a solution.

Because the sensors can operate individually give good 3 star one quite.
FYI: I also use the same Polar Bluetooth heart rate monitor. The recording of speed and heart rate functions together flawlessly with the runtastic Mountainbike app