@fenlyn The reason that Google Search Console is returning the message of “Your Sitemap appears to be an HTML page” is because of the redirect that is occurring for sitemap_index.xml. Because it redirects to a page (the homepage) that is not an XML file, it is trying to read the homepage as an XML sitemap.
As for the redirect itself, we checked on it and it appears to be coming from the Redirection plugin (see image here). We also confirmed this in a cURL test as well:
cbailey$ curl -I https://mdfoodbank.org/sitemap_index.xml
HTTP/1.1 301 Moved Permanently
Date: Mon, 26 Oct 2020 22:42:31 GMT
Server: Apache/2.4.46 (cPanel) OpenSSL/1.1.1h mod_bwlimited/1.4
Expires: Wed, 11 Jan 1984 05:00:00 GMT
Cache-Control: no-cache, must-revalidate, max-age=0
X-Redirect-By: redirection
Location: https://mdfoodbank.org/
Cache-Control: max-age=900, public
Content-Type: text/html; charset=UTF-8
To resolve this, we’d recommend reviewing the redirects in your Redirection plugin and removing any for the sitemap. After removing them, we’d then recommend deleting the sitemap that you submitted in Google Search Console and then resubmitting it.
