Changed mapped subsite's domain. Now, 404 Error.

Everything was hunky dory.

Site at was mapped to

I changed the original subdomain of the main site to

Now anytime I visit the site's frontend, i get 404 errors.

Failed Fix Attempts:

I changed it back to, 404.
I deleted the mapping from within the subsite's admin panel, 404.
I deleted the plugin and reinstalled it, 404.

What do I need to do to this plugin to get it to not 404 after changing a site's url/domain?