If something comes unstuck, it becomes separated from the thing that it was attached to. The brown vinyl covering all the horizontal surfaces is coming unstuck in several places
To come unstuck means to fail. Where economics comes unstuck is when it doesn't take account of the anticipated actions of human beings see also unstick = fail. come unstuck a if a person, plan, or system comes unstuck, they fail at what they were trying to achieve
free; "a man with a mule got my car unstuck"; "the gears locked in second and would not come unstuck"