The Adobe Animate classroom in a book on warped assets - its not working

In the snake charmer exercise, you're supposed to click the

"musical notation bitmap. The bimap becomes a warped asset and a mesh is superiposed on it.

Notice that there are additional control points on the four corner points..."

No matter how many times I try it, there are no control points on the corners, but instead a red and green joint. If I try to delete the joint, it deletes the mesh as well. Help