Hi Jo, Sorry I need to apologise, I read too quickly haha.
I see you are using ACSS, unfortunately, I am not familiar with this plugin but I imagine this is causing the conflict with a possible change made between 1.4RC2 and 1.4 Stable (Again this is just a guess, as not sure how often it is updated or if they have full compatibility with Bricks yet).
There were 3 or 4 bugs reported in 1.4RC2 such as the one below:
And ACSS heavily uses these functions.
I am sure @timmse will be along shortly to help though 
p.s. the site looks very 
great work!