Preview Before Submit: Why are empty fields still appearing on my form?

hey i used a preview before submit but there appears too much unnecessary infomation.
Parents choose an hour from a class (in the example 4C) but also text from all the others classes appears.

How can i mannage only the info from the specific class appears.

I have been testing and I can see the issue you're  reporting, on a cloned form of yours I deleted the preview before submit widget and added it again, this seems to have cleared the error, please also make sure that the include empty fields option is no: 

This worked on my end, if the problem persists, please let us know.