I remember from AC seeming-millenia back that creating a block caused the objects to disappear in model space. The command "oops" causedthem to reappear, with the block available from that point. TC behaves the same way. Creating a block makes the bits vanish, undo/ctrl + Z reappears them, with the block available in the palette.
Compound profile enabled lets this profile extrude,without joining as pline.