Page suddenly redirecting to homepage

I have a client's site with a dynamically delivered visual sitemap page located at website.com/sitemap. It was working flawlessly until recently. For some reason it is now redirecting as a 301 to the homepage.

I feel as though my htaccess file is causing the issue as it seems to be duplicating many lines. Is something in my htaccess is causing this?

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_USER_AGENT} ^Rackspace
RewriteRule . wp-home.txt [L]
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ./index.php [L]
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php [F,L]
RewriteCond %{QUERY_STRING} (\<|%3C).*script.*(\>|%3E) [NC,OR]  
RewriteCond %{QUERY_STRING} GLOBALS(=|\[|\%[0-9A-Z]{0,2}) [OR]
RewriteCond %{REQUEST_FILENAME} -s
RewriteRule ^wp-content/uploads/(.*(secure|Secure|confidential|Confidential|board|Board|director|Director).*(zip|pdf)+)$ dl-file.php?file=$1 [NC,QSA,L]
</IfModule>

# BEGIN W3TC Browser Cache
<IfModule mod_deflate.c>
<IfModule mod_headers.c>
    Header append Vary User-Agent env=!dont-vary
</IfModule>
    AddOutputFilterByType DEFLATE text/css text/x-component application/x-javascript application/javascript text/javascript text/x-js text/html text/richtext image/svg+xml text/plain text/xsd text/xsl text/xml image/x-icon application/json
<IfModule mod_mime.c>
    # DEFLATE by extension
    AddOutputFilter DEFLATE js css htm html xml
</IfModule>
</IfModule>
ErrorDocument 403 /index.php
ErrorDocument 404 /index.php
Options -Indexes
<files wp-config.php>
order allow,deny
deny from all
</files>
Options +FollowSymLinks
# BEGIN W3TC Browser Cache
<IfModule mod_deflate.c>
<IfModule mod_headers.c>
    Header append Vary User-Agent env=!dont-vary
</IfModule>
    AddOutputFilterByType DEFLATE text/css text/x-component application/x-javascript application/javascript text/javascript text/x-js text/html text/richtext image/svg+xml text/plain text/xsd text/xsl text/xml image/x-icon application/json
<IfModule mod_mime.c>
    # DEFLATE by extension
    AddOutputFilter DEFLATE js css htm html xml
</IfModule>
</IfModule>
# END W3TC Browser Cache
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

Thanks for your assistance.