Pressing the sustain pedal turns off the piano one preset in Ableton

In Sunday Keys for Ableton, the sustain pedal may turn off the piano one preset depending on your settings for the remote function of your keyboard input. You may have turned on the remote function if you are wanting to map things in Ableton to your mod wheel, faders, knobs, etc., on your midi keyboard. If this is the case, you will want to make sure to change the MIDI channel of your keyboard, as the default channel 1 MIDI CC 64 (sustain) message is set up to jump to that “OFF” scene.

If you are not mappings any controls to your MIDI keyboard, then you can just turn off the remote function for your midi keyboard in Ableton Live.

You can also go to the Sunday Keys for Ableton Resource Page and watch Video 5: “Mapping controls to your midi controller/keyboard” around the 13:20 minute mark to see how to do this.