Updated to Ubuntu 14.04 (with Apache), .htaccess no longer redirects on 404 errors

Running a few virtual hosts with sites via my droplet, upgraded to Ubuntu 14.04.1, and now none of my previously established 404 redirects work (just getting the default “Not Found - The requested URL /404 was not found on this server.” with a bad URL).

Here is essentially what each of those .htaccess files looks like, for reference:

Options +FollowSymLinks -MultiViews -Indexes

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^(.*)$ $1.html

ErrorDocument 404 /
ErrorDocument 403 /

AddType video/mp4 .mp4 .m4v
AddType video/webm .webm
AddType video/ogg .ogv .ogg

Within the configuration files for the sites-enabled (under /etc/apache2), I have these in place:

        <Directory /var/www/kyleconrad.com>
                Options All
                AllowOverride All
        </Directory>

Like I said, haven’t changed them, haven’t changed any permissions or the like (that I know of), but getting failures with no redirects on 404 errors. Am I missing something here?