Multi-window "Pop up view action" not working even if enabled I ran through settings in Galaxy Note8 and from  there I learned about pop up view action gesture and was able to use it.

But  when I finished running through the rest of the settings (top-to-bottom), I found  the gesture is no longer working even if enabled. Now it does nothing. Why?

What could have been toxic in settings items below Advanced settings item? Was it some accessibility setting?  But I canceled each when it displayed warning  about turning off certain other features. Then I only enabled developer mode.
I also soft-restarted the phone, the problem persists.

How can be pop up view action gesture returned to working normally?
Finally I can see it works, but unlike shown in the visual guide, the dragging needs to start at the very corner of the display (either top left or top right), or (ideally) outside the display, enter the display in the corner and then continue to the center of the display. Then the functionality works as expected.

The effect is also achievable using the S-pen.