FormCraft Form – Not Submitting

I have been using Formcraft for years and never had any issues however on our new site the pop up form on the homepage is not submitting for me and other customers I just get the loading swirl of death.

I have asked others to have a go at submitting and it works 50% of the time,

I have 2 other forms on our website and they all work perfectly just the pop out form on homepage and at the top of all services pages etc.

The page I need help with: [log in to see the link]