lightbox working on one page but not on another

lightbox working on one page but not on another

Hello, I've had lightbox work fine on my site but recently I noticed that it is not working on this page:

I see there is an error in the console:  event.returnValue is deprecated. Please use the standard event.preventDefault() instead.

But I'm not sure what it is that I have done in the page to have this error occur.

Any feedback appreciated!