Nothing about the Freerider app itself has changed for sure.
My first guess is that there might have been some automatic update to the android operating system on your phone that has somehow broken the USB connection.
Also try to rule out the possibility that the USB cable/OTG adapter has somehow broken.
You could try an app called Gamepad Tester to see if it recognizes your controller.
Make sure you are selecting joystick as connection method on the transmitter (not data/mass storage).
(And, when having a problem such as this it sometimes helps to just restart the phone...)