Plugin interferes with Sitemaps

Dear Plugin Author,

I am trying your plugin but it interferes with the Sitemaps.

Please check the link below, you will see the Sitemap is blank:
shorturl.at/bowHL

The problem is resolved when I deactivate your plugin.

Looks like your plugin is adding some kind of code to the Sitemap.

Please advise on how to fix this problem.

Thanks,
Jess

The page I need help with: [log in to see the link]