I have an issue, that my sitemap is not updated anymore. 

SELECT * FROM `core_sitemap` ORDER BY `updated` ASC

I get the date I have updated it manually last time, three days ago. I have made it manually as it was not updated for 4 days till there.

I do not have any errors in admin logs. The tasks log of sitemapgenerator does not have any errors as well. But why there is no new content in sitemap? I have also sorted the table core_sitemap by last_id and see that new items are not in the sitemap. What can cause the issue?

Edit: If I rebuild Sitemap manually from ACP, then it is up-to-date and contains new items as well.

Sounds like the task isn’t running. Do you have a cron job set up to run tasks?

Yes, it's cron. And the task is running according to task log every 15 minutes. There are no errors in the task logs, that's why I do not understand what is wrong.

I'd recommend submitting a ticket