带有锚点的MediaWiki URL截断URL

If I try to access a page on my MediaWiki, with a URL such as:

http://www.mywiki.com/some_page#a_section_of_some_page

the URL gets truncated to:

http://www.mywiki.com/some_page

I am running in IIS and using short URLs. In my LocalSettings.php, I have

$wgScriptPath = "";
$wgScriptExtension = ".php";
$wgArticlePath = "${wgScriptPath}/$1";
$wgServer = "https://www.mywiki.com";
$wgUsePathInfo = false;

I have a rule in my web.config like this:

<rule name="wwwroot">
   <match url="^(.*)$" />
   <conditions>
      <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
      <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
   </conditions>
   <action type="Rewrite" url="index.php?title={UrlEncode:{R:1}}" />
</rule>

I just wrapped the capture group in UrlEncode, but obviously it is not working. Also, oddly enough in the blink of an eye when I click a external link to

http://www.mywiki.com/some_page#a_section_of_some_page

I can see the browser go to the correct page, but then "#a_section_of_some_page" gets stripped out of the URL and the browser redirects to the top level page.