I submitted a bug, but it seems like they can't reproduce the problem.

Please try this…

1. Drop a Null in your scene.
2. Press 2 to select points. An Edit SOP will be place inside the NUll object.
3. Move some points
4. Press u to go out to object level.

The Null object disappears from the viewport on my side.

Let me know if you get the same.

I think I know what is up in H15.

In H15, all the pre-built Null geometry pieces have an equivalent accelerated method to draw very fast in OpenGL. This does make a very large difference in viewport drawing performance.

By editing the null shape, I bet this breaks the drawing in the viewport.

Not so much a bug but more of a don't do this if you want accelerated drawing of nulls in the viewport.

But I would have expected the Custom option to draw any geometry input to this null and bypass the accelerated option.

Just get back to Support with the above details and to have a bug submitted for the Custom option not working with any input.