we have our personal theme.

The custom theme you are using, developed by you?

If yes please leave the example URL  to allow us to check it. 

If no, you should contact the custom theme developers, and ask them this question.

Problem With wpDiscuz, comments don't display. "2 Comments" displays, and then the form displays fine, just not comments.

Did anyone solve this problem at last?

we have this problem too. but we don't use Divi theme. we have our personal theme.

For me it requires login, even if login is not required in settings. Hmmm...

Please navigate to Dashboard > Comments > Forums admin page, make sure the "Allow guests to comment" option is enabled.

More info here: https://wpdiscuz.com/docs/wpdiscuz-documentation/getting-started/custom-comment-form/comment-form-settings/#only-loggedin

Here is how to make a shortcode that might side-step the Divi comment system. This sortof worked, but comments appeared above the normal content. Weird.

Use the following code, it will work properly:

function my_wpdiscuz_shortcode() {
    if (file_exists(ABSPATH . 'wp-content/plugins/wpdiscuz/templates/comment/comment-form.php')) {
        ob_start();
        include_once ABSPATH . 'wp-content/plugins/wpdiscuz/templates/comment/comment-form.php';
        return ob_get_clean();
    }
}

add_shortcode('wpdiscuz_comments', 'my_wpdiscuz_shortcode');

Here is someone who says he does it without any issues. I can confirm that it sortof does work if (a) you find all the Divi shortcodes a page uses, then (b) use the default editor, pasting in all the shortcodes, finally (c) check the Discussion > Allow Comments box... wpDiscuz does work. For me it requires login, even if login is not required in settings. Hmmm...

Here is how to make a shortcode that might side-step the Divi comment system. This sortof worked, but comments appeared above the normal content. Weird.

I will investigate further.

Could you please check using a default theme? 

Problem With wpDiscuz, comments don't display. "2 Comments" displays, and then the form displays fine, just not comments. If I deactivate the plugin, the comments are displayed.

I have no cache installed yet. I use the Divi theme. No other extensions handle comments, and I disabled them all to see if they effected the situation... nothing.

tia...