Thank you page not showing

When my clients send in their forms a thank you page doesn't come up. This blank square appears instead. Thanks!

I have cloned your form, and after submitting it, the Thank You page showed up:

Please try embedding your form with the Iframe code: https://www.jotform.com/help/148-Getting-the-Form-iFrame-Code 

If the issue continues, could you allow us to submit your form to test further?