used to play on android no problem but now no usb controller sticks input detection on calibration tab radiomaster tx16s open tx
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...)
I see, well, I don't really have any other ideas, it's difficult to know. Since it worked before it seems it must be something that has changed on your device. Perhaps you can try to think if there was any specific point in time when it stopped working, and if there was any change made around that time.