Hello,
Thanks for contacting support.
The common reasons for a post not appearing in the sitemap are sometimes caused by the following:
1. Item set to no-index in Rank math > Titles & Meta or individually.
2. The sitemap being cached on your site locally or at server-level. For this head over to WordPress Dashboard > Settings > Permalinks and hit the save button once. Go to WordPress Dashboard > Rank Math > Sitemap Settings and hit the save button once.
3. The canonical is set manually in the advanced tab.
Hope that helps.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.