I have been pecking away when I have time at home on a small renovation job, which I had been previously messing with at work.
One of the tasks was to put in a small stair. The problem was to actually see what was going on, and luckily I remembered the 3D sectioning tick box.
Tick this and you can see what is happening quite easily. Please note this is still work in progress.
The other was a porch over the old front door. Yes, the door was removed, but in 2D land the porch stayed behind. Not noticed among all the other goings on, but immediately obvious upon rolling the model round in 3D for a look.
This is the Autocad flat view of the same part, as existing:
The note is one I have just added.