You are showing the "upcoming tracks" which is the order within the shuffle list ie. the order that tracks will play on completion of each track or clicking the next track button. Thats not the same as the order of the tracks on the "playing tracks" list eg. you might have tracks 1,2,3,4 from an album on the playing tracks list (switch the view to "playing tracks" and it will show the tracks in order 1,2,3,4) but when shuffle is enabled the tracks might play in order 3,1,2,4. In the upcoming tracks view the display order will be 3,1,2,4
The api is moving the order of tracks in the playing tracks list, not the sequence within the shuffle order.
Having said that, there might be a display bug in the upcoming tracks view as i would expect the moving tracks with api call would have no effect on the tracks displayed in that view.
But it doesnt change that the api is not moving tracks in the shuffle order