I did a fix that it might help, at least not to get the warning on the site.
1) Access to the file /wp-content/plugins/responsive-lightbox/includes/class-frontend.php
2) Change line 719 for this one:
$include = array_unique( array_filter( array_map( ‘intval’, explode( ‘,’, (string) $shortcode_atts[‘include’] ) ) ) );
You can check that the only change has been adding the “(string) label”
I hope it might be of help