See this post
I was able to fix both sitemap & news site map on my one site.
I consider this a band aid rather than a fix.
I was hoping the above would work, but I must be the unlucky one. When I click on you can find your xml sitemap here the button that follows this statement, it still brings me to a 404. The file it is pointing to as well is not named sitemap.xml but the following
'http://serverdirectory/wordpressdirectory/sitemap_index.xml'
Not sure why, but the above fix err bandaid didn't work. Thank you so much for sharing though dmiyares.
Joseph