Shadowbox JS working in blog but not gallery

This has worked fine for months/years but has stopped. Here’s the blog where shadowbox works fine when you click on images:

architecturalvisualisation3d.co.uk/blog/

and here’s a nextgen gallery where it doesn’t work:

architecturalvisualisation3d.co.uk/portfolio/

I use rel=”shadowbox” for the gallery. Total line of code is:

[nggallery id=1 rel="shadowbox"]

Would love some help. Thanks!