Right, I've had a bit of a play and the problem seems to be when I use the call back scripts.
The plugin recommends that if you use Analytics, you need to set two callback scripts to fire: onAccept and onCookiesAllowed.
I've removed them individually and re-loaded my pages, after clearing the ”civicAllowCookies“ cookie each time.
I found that the onAccept callback seems to be the one interfering with letting someone click, “I am happy with this”. Using only the callback for onCookiesAllowed allows the cookie to be set, the icon stays green and minimised for the remainder of the time browsing around the site.
I'm presuming that this will affect my analytics data and only register a site visit from the following page load. I'll be monitoring this closely.
This law is a total hassle for small businesses. If it affects my site too much, I may have to remove the plugin and rely on implied consent...