Editions and Excerpt “drop-downs” not working

Hi,

We’re experiencing an issue with the Editions and Excerpt “drop down” links. The little plus sign next to each Edition/Format and the Read More link in our Excerpts doesn’t function anymore. Please see example here: https://www.rowanartistry.com/book/a-study-in-silks/

This happened a few times during development of the site, but someone else fixed the issue, so I’ve no idea what they did to correct it. I’m also not sure when or how the problem returned.

If you could help look into this and suggest a fix, that’d be great. Thanks in advance!