Why does TWiki return a 404 for Main/WebHome?

Question

I've attempted to follow the guide at https://twiki.org/cgi-bin/view/TWiki.ShorterUrlCookbook to shorten the URLs used in my TWiki installation. It's installed on Ubuntu 16.04 with Apache 2.4 and Perl 5.22. TWiki is served as a virtual host, and was served successfully before I followed the URL shortening guide.

Here is my current configuration: The Apache config file twiki.conf has the following, just as given in the URL shortening guide

ScriptAlias /bin        "/var/www/twiki/bin"
Alias       /pub         "/var/www/twiki/pub"
Alias       /pub/Sandbox "/var/www/twiki/pub/Sandbox"
ScriptAlias /pub         "/var/www/twiki/bin/viewfile"
Alias       /           "/var/www/twiki/bin/view"

The /var/www/twiki/lib/LocalSite.cfg configuration file has

$TWiki::cfg{ScriptUrlPath} = '';
$TWiki::cfg{ScriptUrlPaths}{view} = '';

The front page of the installation loads just fine at http://wiki.mysite.com/. When I try to follow a link on that page to one of the Webs, though, like http://wiki.mysite.com/Main/WebHome, I get a 404 for

The requested URL /Main/WebHome was not found on this server.

I used to have a context prefix MySite in TWiki URLS, such as http://wiki.mysite.com/MySite/view/Main/, but I've attempted to remove it. I wouldn't be surprised if that's the source of the error, but I really have no way of knowing, given the state of TWiki and Foswiki documentation.

What am I missing?