I have recently noticed that for at least one of my projects, the sitemap.xml file is not getting updated online. I have toggled the checkbox, rebooted the computer, and re-uploaded the entire site. I still end up with the same old sitemap.xml file that has old pages in if from months ago.
I deleted the sitemap.xml file online, and when I re-uploaded the updated site, it uploads an old sitemap again.
Using an FTP package, check if you have multiple sitemaps on the server. If so, remove all of them and republish. They should be in the public_html folder or equivalent. You may also be able to do this through your hosting control panel file manager
I don’t have multiple sitemaps. I have deleted them and re-published. It keep generating the same file. The date stamp on the new sitemap.xml file current… the contents are old. Very strange.