seo – Google could not retrieve the sitemap

Sitemaps are an integral part of our Web work. And we need them to get more love from Google. But for about a month, I can not send sitemaps to the Google Search Console.

I've used https://technicalseo.com/tools/fetch-render/ to check and I go through it successfully. I used the sitemap validator and that too showed no errors. It seems that something is wrong with the search console.

Yesterday, I started another site and used the same wordpress plugin to generate a site map, then the same gmail login to connect to the search console. I have tried to add a property.

If I submit a new sitemap, it can not fetch, and if I try to resubmit an existing plan, it succeeds, but the date of the last reading is 6 months. So I guess it does not work.

What are the possible solutions. Live tests indicate that it is impossible to extract because it is a noindex. I think there's nothing wrong with keeping sitemaps without indexes because sitemaps should not show up in searches. Infact my second domain also had sitemaps submitted with noindex

I use WordPress php 7.3 and HTTP / 2

My sitemap url is https://milyin.com/sitemap.xml.

My HTTP headers are:

HTTP/2 200 
server: nginx
date: Thu, 22 Aug 2019 12:23:21 GMT
content-type: text/xml; charset=UTF-8
vary: Accept-Encoding
x-robots-tag: noindex, follow
link: ; rel="https://api.w.org/"
last-modified: Wed, 21 Aug 2019 14:03:48 GMT
etag: W/"59184deaadc3de11f553f5a8fbaac7f0"
x-httpd: 1
x-robots-tag: index, follow
host-header: 192fc2e7e50945beb8231a492d6a8024
x-proxy-cache: MISS
content-encoding: gzip