: URLs not allowed error for one property, but not for the other? All of our XML sitemaps are located on another domain than the domain they're referring to, for instance: - Sitemaps would be

Posted in: #GoogleSearchConsole #Indexing #Sitemap #XmlSitemap

All of our XML sitemaps are located on another domain than the domain they're referring to, for instance:
- Sitemaps would be located at sitemap-domain.com/sitemap-1.xml
- URLs being referenced in those sitemaps would be located at main-domain.com

+++ ISSUE 1 +++
URLs not allowed
We verified ownership for both domains in the Search Console. There are tons of sitemaps where this worked fine for us, however, since Friday, there is one sitemap - let's call it "sitemap-index-fluff.xml" - where we get the "URL not allowed" error notice when submitting the index sitemap on our sitemap-domain.com.

Since all of our sitemaps can be accessed at each property/domain, we submitted the sitemap twice in the Search Console, once for each property:

sitemap-domain.com/sitemap-index-fluff.xml
main-domain.com/sitemap-index-fluff.xml

Please note: All sitemaps referenced in sitemap-index-fluff.xml are still located at sitemap-domain.com, whereas all URLs within these sitemaps are located at main-domain.com. All sitemaps have been checked for syntax errors or 4xx/5xx/3xx status codes before submitting.

Now this is what happened:
- The sitemap index located at sitemap-domain.com showed as many errors as URLs ("URLs not allowed").
- The sitemap index located at main-domain.com began with the same amount of errors. However, the number is reduced day by day, and the number of indexed pages (roughly 10% of what we submitted currently) as well. It just goes on ever so slowly.

Now I am wondering why this is working with our main-domain.com property and not with our sitemap-domain.com property, since this has been working fine with exactly the same setup for a lot of other sitemap indexes in the months? Any ideas on this?

+++ ISSUE 2 +++
Sitemaps not clickable in the Search Console
While we're at it, there's another error I have never come across before: Whenever a sitemap the Search Console pulled from the sitemap index shows an error, you can usually click the sitemap (Crawl > Sitemaps > Sitemap index) and see the errors for each individual sitemap with some sample URLs.

Funny thing is: When submitting the sitemap index to our sitemap-domain.com property, the sitemaps are clickable as usual. When submitting the sitemap index to our main-domain.com property, Search Console still pulls all sitemaps from the sitemap index and shows the number of errors for each individual sitemap - but none of these are clickable.

Has anyone ever come across this issue? Is this a Search Console bug, or is this something we can fix by ourselves? If so, how?