CSS Helper is not showing all code on some forms.

I've been working on editing a set of forms for my company's website. To set consistent styling I've been altering the CSS in each form.
This has been a straightforward task via the CSS Helper in all but one form and I'm not sure why.
Whereas in every other form the CSS helper shows all the CSS in the form and is editable in this form it only shows a few #IDs and all the brackets are empty.

This is how the CSS Helper normally appearsand this is how it appears on the problem form

The designer is showing all the ID's in the form. They are probably empty because they don't have any style associated with it. 

Could you provide a link to your form so we can test it?

We'll wait for your response.