Won't work since WP update

The slideshow on the page you linked to appears to be OK to me. Did you get this sorted out?

Adding the custom field wpautop > false to each individual post fixes it. But that kills the auto paragraph functionality of WP and will mean going through every post, checking if gss is in it and editing the post.

This links to an un-fixed post. ie a post without wpautop turned off.
https://www.celticquestcoasteering.com/national-tourism-awards-wales-2013/

As you can see there’s this text…

data-cycle-speed="750"
data-cycle-center-horz="true"
data-cycle-caption="#gslideshow_captions"
data-cycle-caption-template="{{alt}}"
>

Followed by all the images running vertically down the page.
Slideshow functionality is dead.

I’ve tested the GSS plugin in the latest version of WP (4.5) and it seems OK on my platform. On your site some function is inserting wpautop type tags (<p>, <br>) in your slideshow output. As far as I know wpautop should not be executing inside the gss shortcode. This leads me to believe that it is your theme or one of the plugins on your site that is responsible. In order to troubleshoot I’d suggest 1) switching to the default WP theme and/or 2) deactivating your plugins one by one to see if that fixes the problem.

Lastly you could try adding the code below to your theme’s functions.php file. I found this code online, haven’t tested it and reprint it here with no warranty of any kind:

//move wpautop filter to AFTER shortcode is processed
remove_filter( 'the_content', 'wpautop' );
add_filter( 'the_content', 'wpautop' , 99);
add_filter( 'the_content', 'shortcode_unautop',100 );

I hope it goes without saying that your [gss …] shortcode in the visual editor should not contain any returns inside the brackets.

Good luck and let us know how it goes.

Marking topic as resolved.