By that I mean one that isn’t of obvious dramatic story conflict.  When someone wants to do something and there is no obvious source of who they are going up against, yet it’s still something that needs to be overcome for consequential reasons.   I can’t think of a specific example now, only that those sorts of things have come up in the past.  The question of is this a hand wave and move on moment or is there actually something that is opposing the action so we need to roll it out.