There seems to be a problem with replying to forum posts when using Corporacy. If I switch to Twenty Twenty-Two 1.2 theme then it works correctly.
The problem is that when a post is displayed it has the link xxx.com/post-name/#respond with the title “leave a reply”. But clicking this simply shows the full post but no form to enter a reply.
As I say, switching to a standard theme fixes this.

“Catch Themes Demo Import” plugin says;

There are no predefined import files available in this theme.

Can you share XML, WIE/JSON and DAT files, plaese?
So, we can upload the import files manually.