Control of a slope for a conduit is a common practice when designing drainage network.
For now, when Set invert to Start/Stop are true, the slope manipulators are greyed out.
The only solution to update model is to move / enter new elevation for the node.
So there are no way to force a pipe slope, and now way to move node specifying a slope.
Civil Accudraw does not work.
It's a severe limitation, since again specifying a pipe slope is a common request in drainage design.