为什么--cycle在这里不起作用？

Question

我正在尝试绘制一个三角形，其顶点位于圆的三等分点。奇怪的是，当我使用时\draw[thick] (u) -- (v) -- (w) --cycle，它会错过一条边 uw。这是为什么？\draw[thick] (u) -- (v) -- (w) --(u)工作正常。

\documentclass{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
\begin{scope}[xshift=-5cm]
  % Dividing the circle into thirds
  % Defining the required angles and labels for the first set of nodes
  \foreach \angle/\label in {30/u, -90/v, 150/w} {
    % Drawing the points and labeling them
    \node at (\angle:2) [circle,fill=white,draw=black,inner sep=2pt] (\label) {$\label$};
  }

  % Connecting the three points to form a triangle
  \draw[thick] (u) -- (v) -- (w) --cycle;
\end {scope}
\begin {scope}
  % Dividing the circle into thirds
  % Defining the required angles and labels for the second set of nodes
  \foreach \angle/\label in {30/u, -90/v, 150/w} {
    % Drawing the points and labeling them
    \node at (\angle:2) [circle,fill=white,draw=black,inner sep=2pt] (\label) {$\label$};
  }

  % Connecting the three points to form a triangle (closing the shape)
  \draw[thick] (u) -- (v) -- (w) -- (u);
\end {scope}
\end{tikzpicture}
\end{document}