Gaps between images

After the latest update of WordPress, I notice that the slider was no longer appearing at the bottom of my page here: https://alanahelbig.com/
To work around this, I uninstalled and reinstalled the plugin, deleted all the settings from the Appearance > Widget area and then recreated a new shortcode in the widget area.

This seemed to fix the issue, however, previously when I used the template: Thumbnails – without border – the images sit perfectly alongside each other with no gaps.

Now the images have a strange wide white gap between each image which doesn’t look great.

Can you please help?

Thanks.

The page I need help with: [log in to see the link]