Bluetooth page turnerpedals send the same 'up', 'down', 'left' and 'right' keyboard commands as a wireless bluetooth computer keyboard.
iOS identifies connected bluetooth page turner pedals as an external keyboard and will hide the iOS on-screen keyboard. When the iOS keyboard is hidden Song One displays a customon-screen keyboard.
Disable Song One's on-screen keyboard when using an external Apple keyboard. Go to Song One's settings/preferences (under 'Devices' -> 'Mobile Devices') and deselect the option 'Show On-Screen Keyboard When Using Bluetooth Devices' .