Wrong class applied on homepage

Hi
Thanks for a great plugin!
Recently I discovered some odd behaviour on our homepage. The content got very narrow on desktop. After inspecting the source code I realised the class of content is incorrect. <div id=”content” class=”grid col-620″> when it should be (and has always been) <div id=”content” class=”grid col-940″>. No matter what I changed it would not display right. It only happens on the homepage and has also happened on another site (local). I have done a temporary fix by adding a .grid col-620 {width:100%;}
Any ideas why this has happened? plugin and wordpress on the latest versions.
http://www.photographycourselondon.com

Thanks

https://ww.wp.xz.cn/plugins/siteorigin-panels/