Hello,
You need to edit the file basel\inc\shortcodes\shortcodes.php and replace the code
$link = wp_get_attachment_image_url( $img_id, 'full' );
$image_sizes = getimagesize( $link );
with this one
$image_data = wp_get_attachment_image_src( $img_id, 'full' );
$link = $image_data[0];
and also this part
<a href="<?php echo esc_url( $link ); ?>" data-index="<?php echo esc_attr( $i ); ?>" data-width="<?php echo esc_attr( $image_sizes[0] ); ?>" data-height="<?php echo esc_attr( $image_sizes[1] ); ?>" <?php if( $target_blank ): ?>target="_blank"<?php endif; ?> <?php if( $caption ): ?>title="<?php echo esc_attr( $title ); ?>"<?php endif; ?>>
to this
<a href="<?php echo esc_url( $link ); ?>" data-index="<?php echo esc_attr( $i ); ?>" data-width="<?php echo esc_attr( $image_data[1] ); ?>" data-height="<?php echo esc_attr( $image_data[2] ); ?>" <?php if( $target_blank ): ?>target="_blank"<?php endif; ?> <?php if( $caption ): ?>title="<?php echo esc_attr( $title ); ?>"<?php endif; ?>>
Regards
.
