If the exit portal from a monolith map is opened at just the correct position in front of a forge, the portal clips through the forge and becomes impossible to select.
Note that, for SC players, it is possible to die on the map to return to Echo of a World with no ill effect, beyond the death itself. (The chest and conquered counter persists.)
Update: Corollary to this issue, if you already cleared the objective and have the dialog box to open the portal, die, return to Echo of a World, you can still open the portal which appears to not do anything.
