I put BabylonJS scene with the ArcCamera in StoryBook and noticed that when you:
- press the mouse button to drag your camera around scene
- drag it outside frame of StoryBook (still holding the button to drag)
- realis mouse button outside the StoryBook iframe
- return to the iframe with a released mouse, the ArcCamera is still dragging your view.
So it’s not detecting mouseUp outside the iframe.