Issue: Comment section not displayed on all posts in WordPress.
Have seen an issue where some blog posts displayed a comment section and others did not. In troubleshooting it turned out a setting was enabled to close the comments section after the blog post reached a certain number of days old.
Solution:
Login to the sites WordPress admin console.
Browse to Settings > Discussion.
Here in the ‘Other comment settings’ is an option to Automatically close comments on articles oler than X days.
Uncheck this box to display the comments section on all your blog posts regardless of the articles age.