The issue is that the touch input for the orbit camera doesn’t track the touch id of what is controlling it so it get confused when there are 2 touches on the screen as you are finding out.
If we get rid of the zoom in/out pinch gesture, that will make this easier to handle.
The other issue is that when you move your joystick, the touch event is consumed by the joystick so that the world doesn’t get any input. This prevents the touch controls for the camera getting the event to update.
Your best bet here may actually to use an element like a touchpad instead.
I’ve done a very quick example here so you can see what I mean:
https://playcanvas.com/project/1020936/overview/f-touch2