If you are using PWM protocol, it would be a good test to plug a servo in to the receiver roll channel to make sure it is working. Even if not currently using PWM, it would be a good debug procedure to set your receiver into PWM mode and make sure all the channels work.
Also, modern transmitters can be configured any of several ways that would make this happen.
Also be aware that you must be careful to not move any channel except the one you intend to move during transmitter calibration.
As a general rule, you want a default transmitter setting for fixed wing (not heli) since the FC needs simple, unmodified stick positions.