When adding an element to the DOM or styling that causes the element being dragged to move at the same time that the drag is starting, the drag ends instantly. This makes it impossible to introduce new items as dragTargets if they potentially move the element being dragged.
This bug is also mentioned here: https://github.com/react-dnd/react-dnd-html5-backend/issues/18
Could you provide a reduced test case showing this? It's true that we bail if the "dragstart" handler mutates the DOM in a way that destroys the drag source element's RenderObject, but my understanding is that just moving the element should not abort the drag session altogether.
Additionally, it might be interesting to know whether this reproduces on iOS (I would expect it to also reproduce, which would indicate this is an issue at the WebCore layer rather than the client layers.)