These handles only show the true position of the vertex, and only if it is far enough away from where it would be on the dynamically subdivided preview. So on a dense mesh, you’re not likely to see these handles appear since the subdivided surface won’t be changing drastically from the base level. Pull a point far enough away from the surface and you should see them start to appear.
Also note that your zoom level can also affect if these handles appear or not. If you zoom out, then you won’t see these handles (probably for the better as they’d just get in the way). Zoom in close enough and they’ll start to appear.
Basically you just need to have enough screen-space distance between the vert’s two positions in order for it to be in the tolerance range for the handle to appear.