Trackback error Adelle 10.1

I installed Adelle yesterday and noticed today that there is a problem with displaying trackbacks. Each individual ping / trackback generates this error on the page where the trackback should be displayed:

Warning: call_user_func() expects parameter 1 to be a valid callback, function 'comment_style' not found or invalid function name in /home/content/66/9573966/html/wp-includes/comment-template.php on line 1334

You can see what I mean at the bottom of this post, below the comments.

‘comment_style’ isn’t found in line 1334. Here’s 1333 – 1336:

if ( !empty( $args['callback'] ) ) {
			call_user_func( $args['callback'], $comment, $args, $depth );
			return;
		}

I know absolutely nothing about how to resolve this, so any help would be greatly appreciated!