Installed WPDiscuz a few days ago. Comment section was where it was supposed to be and even had the comment count - but no comments were showing.

Looked around for answers and finally did the disable plugins routine. Security Optimizer (SiteGround) was the culprit. Did a chat with them and it was an issue with Lock and Protect System Folders. If you use the plugin: Security Optimizer >> Site Security >> Manage Security >> Lock and Protect System Folders - toggle OFF.

Thought this might help someone.