I would suggest you to go and re-submit your sitemap again and then wait for few days to see the difference.
Another thing which can think of is to go and check the setting of your SEO tool for all the single post you have newly published. For example, if you are using Yoast SEO then for each post check your Yoast SEO setting. Check if you have noindex turned on those post by mistake?
Yoast SEO - Open any post in edit mode – Go Down to Yoast SEO --> click on settings gear symbol - then check what you have on META Robots Follow ( Default for post type , currently:index should be the one your need)
I hope this helps.