Non-canonical URLs remain in sitemap.xml

Hello, I am having two issues:

1. Non-canonical URLs in the sitemap.xml.

Google explicitly says List only canonical URLs in your sitemaps.

This means that declaring a canonical URL-A for a page or post with URL-B should automatically remove the URL-B from the sitemap.xml.

It seems it doesn’t work like this currently, as non-canonical URLs are being included in the generated sitemap.

2. Canonical URL for a tag page disappears in the Ghost admin app interface.

Once I declare a canonical URL for a tag page (in the “Meta data” section), click save, close, and then go back - the canonical URL disappears. Tested in the web app and desktop app, different tag pages, various urls. When I check with 3rd-party tools if the tag page has become non-canonical - it has. But in the app interface the “canonical URL” meta data field remains empty. Looks like a bug.

Please advise how to fix or overcome these 2 issues.

Thank you.