I tried deleting snippets of code on the single portfolio php using the Virtue theme but I couldn’t get it to work. I ended up commenting out the one line that references $post_id = get_post_thumbnail_id() which seems to work.
Snippet of code that was updated:
<?php } else if ($ppost_type == ‘none’) {
$portfolio_margin = “kad_portfolio_nomargin”;
} else {
// $post_id = get_post_thumbnail_id();
$img_url = wp_get_attachment_url( $post_id);
$image = aq_resize( $img_url, $slidewidth, $slideheight, true ); //resize & crop the image
if(empty($image)) {$image = $img_url; }
?>