最后覆盖不起作用的问题：

Question

希望你们一切都好！我在我的一个文件中使用过这个颜色框，但我对其进行了编辑，以便可以通过添加覆盖键来破坏它，无论如何，这是我的代码和编译后的结果：

\documentclass{article}
\usepackage{tikz}
\usepackage{lipsum}
\usepackage[most]{tcolorbox}

\newtcolorbox[auto counter]{exo}[1][]{%
    enhanced, breakable, fonttitle=\large\bfseries,
    title=\raisebox{-2pt}{\textcolor{blue}{E}},
    left=\tcboxedtitlewidth,
    boxsep=0pt, top=2mm, right=2mm, bottom=2mm+0.7\baselineskip,
    sharp corners, colback=white, colbacktitle=blue, frame hidden,  opacityback=.5,
    pad before break=-0.7\baselineskip,
    before upper = {\begingroup
        \large\bfseries\textcolor{blue}{xercice }
        \textcolor{red}{\thetcbcounter} \quad\endgroup},
    attach boxed title to top left={
        xshift=2pt,
        yshift=-\tcboxedtitleheight+1.5pt-2mm},
    boxed title style={
        empty, left=0mm, right=0mm, top=0mm, bottom=0mm, boxsep=2pt},
    underlay boxed title={
        \path[fill=red] (title) circle (\tcboxedtitleheight/2);},
    overlay unbroken={
        \coordinate[xshift=\tcboxedtitlewidth/2,
        yshift=-\tcboxedtitleheight-0.7\baselineskip] (nw) at (frame.north west);
        \node (sw) [circle, fill=red, inner sep=2pt,
        xshift=\tcboxedtitlewidth/2, yshift=\tcboxedtitlewidth/2]
        at (frame.south west) {};
        \draw[blue, line cap=round, line width=2pt,
        dash pattern=on 0pt off 4\pgflinewidth] (nw) -- (sw);},
    overlay first={
        \coordinate[xshift=\tcboxedtitlewidth/2,
        yshift=-\tcboxedtitleheight-0.7\baselineskip] (nw) at (frame.north west);
        \coordinate[xshift=\tcboxedtitlewidth/2,
        yshift=0.7\baselineskip] (sw) at (frame.south west);
        \draw[blue, line cap=round, line width=2pt,
        dash pattern=on 0pt off 4\pgflinewidth] (nw) -- (sw);}
    overlay last = {
       \coordinate[xshift=\tcboxedtitlewidth/2,
        yshift=-\tcboxedtitleheight-0.7\baselineskip] (nw) at (frame.north west);
        \node (sw) [circle, fill=red, inner sep=2pt,
        xshift=\tcboxedtitlewidth/2, yshift=\tcboxedtitlewidth/2]
        at (frame.south west) {};
        \draw[blue, line cap=round, line width=2pt,
        dash pattern=on 0pt off 4\pgflinewidth] (nw) -- (sw);
    } ,#1}


\begin{document}

\vspace*{12cm}


\begin{exo}
\lipsum[1]

\lipsum[2]
\end{exo}

\end{document}

如上图所示，盒子的第二部分没有按照我想要的方式框起来。有什么想法或思路可以解决这个问题吗？提前谢谢！