Comments not displaying in Custom Post Type

We have a custom post type (Questions), but we're finding that when comments are submitted, though they display within the Post's edit screen the Comments section in Wp Admin > Comments is empty. They're obviously going into the database, but not sure where.

So when we include comments.php, the 'leave a comment' section is displayed, but any previous comments are not (screenshot attached – there should be two comments displayed in this post).

We've enabled comments in the Settings for this Post type as well as in the individual posts.

Are we doing something wrong? Perhaps we need to create a custom comments.php file and call the comments from somewhere else?

Thanks for your help,
Dave