Hello,
Please add this filter to your website:
add_filter( 'rank_math/sitemap/enable_caching', '__return_false');
Here is a guide you can follow to add the filter:
https://rankmath.com/kb/wordpress-hooks-actions-filters/
Once done, clear your website cache, and check the sitemap.
For the Schema warnings, please ensure that you have entered all the details in the Local SEO settings in Rank Math.
https://rankmath.com/kb/local-seo/
Hope this helps.
Thank you.