[sptau]

Ohhhhhh, It's working perfectly now.

I suspect that the issue where "the last TOC entry in the Table of Contents appears on the first" is not unique (I've observed this in over ten epub files).
The epub toc.ncx looks like this:

......
    <navPoint class="chapter" id="num_2" playOrder="2">
      <navLabel>
        <text>太平广记（第一册）</text>
        <!-- The Book Title -->
      </navLabel>
      <content src="text/part0001.html"/>
      <navPoint class="chapter" id="num_3" playOrder="2">
        <navLabel>
          <text>封面</text>
          <!-- Cover -->
        </navLabel>
        <content src="text/part0001.html"/>
      </navPoint>
      ......
    </navPoint>
......

And the UI looks like this:
| 源内容 | 目录项 |
| OEBPS/Text/part0001.xhtml | 封面|太平广记（第一册） |

The test version you provided has effectively resolved this issue.
The UI looks like this NOW:
| 源内容 | 目录项 |
| OEBPS/Text/part0001.xhtml | 太平广记（第一册）|封面 |

I am immensely grateful for your help.