External mixer mode. Pitch bend +/- buttons disappear???

When I connect my iPad to to an external mixer (via USB) I have an external mode radio button in the settings panel.

When I turn that on the +/- buttons on the waveform to pitch bend disappear.

How can I pitch bend on screen when using external mode radio is on.

See pics https://photos.app.goo.gl/yrefHSFahRJvj9U17