title: My simple react-dnd is not working - dragging an item causes the entire list to disappear
body: <p>I am trying to get this react-dnd code to work using the react-beautiful-dnd library.</p>
  
  <p>I am not sure but for some reason my 2 lists disappear the moment you start to drag an item.</p>
  
  <p><a href="https://codesandbox.io/s/jvq5815nvy" rel="nofollow noreferrer">https://codesandbox.io/s/jvq5815nvy</a></p>
  
  <pre><code>return (
        &lt;DragDropContext onDragEnd={this.onDragEnd}&gt;
          {board.lists.map((list, index) =&gt; (
            &lt;Droppable droppableId={list.name}&gt;
              {(provided, snapshot) =&gt; (
                &lt;div
                  ref={provided.innerRef}
                  style={getListStyle(snapshot.isDraggingOver)}
                &gt;
                  {list.cards.map((card, index) =&gt; (
                    &lt;Draggable key={card.id} draggable={card.id} index={index}&gt;
                      {(provided, snapshot) =&gt; (
                        &lt;div
                          ref={provided.innerRef}
                          {...provided.draggableProps}
                          {...provided.dragHandleProps}
                          style={getItemStyle(
                            snapshot.isDragging,
                            provided.draggableProps.style
                          )}
                        &gt;
                          {card.title}
                        &lt;/div&gt;
                      )}
                    &lt;/Draggable&gt;
                  ))}
                  {provided.placeholder}
                &lt;/div&gt;
              )}
            &lt;/Droppable&gt;
          ))}
        &lt;/DragDropContext&gt;
      );
  </code></pre>
  
  <p>It seems like clicking and dragging an item messes up, which I though was maybe the key value of the element but I can't see what I am doing wrong.</p>
  
  <p>The devs who made the library created a sample sandbox with working code that I tried to mimick: I simply modified the example sandbox for the library </p>
  
  <p><a href="https://codesandbox.io/s/ql08j35j3q" rel="nofollow noreferrer">https://codesandbox.io/s/ql08j35j3q</a></p>
  
  <p><strong>Can anyone see what I am doing wrong?</strong></p>