The vertex stars form an open cover of : every point has a nonempty positive-coordinate support, and therefore belongs to the star of at least one vertex. At a vertex itself, only its own barycentric coordinate is positive. Thus belongs to its own star and to no other vertex star.
Any finite selection of stars omits every vertex not among their finitely many labels. Infinitely many vertices therefore prevent a finite subcover, provingNo local-finiteness hypothesis is needed for this vertex-star cover obstruction to compactness.