Post permalink is not working

Hi

I have faced this problem in couple of blogs. I changed my permalink to custom structure /%posttitle%/. The individual post the permalink show https://siteurl/%posttitle%/ instead of the post title.

here is the site where I am facing the problem

https://table99.com/ (under construction)

In the recent post, you can see the link is pointing to https://table99.com/%posttitle%/

Thanks