Post not getting indexed

Hi There,
My site is based on news so I want my post to get indexed as soon as possible. Everything was fine before and my post used to get indexed within a minute after posting articles and it used to appear on google.

But past few weeks the indexing has been really slow and post takes more than 5 hours or sometime even a day. On webmaster tools when I try to inspect url it says url not indexed. Some time it says url is on google but when I check the link on google search it does not appear there.

Please How do I fix this issue?

Thanks