Form showing blank page after submission

Hello,
I have installed a contact form on my website: markustracy.com. It works really well however once someone submits their message, their computer screen goes blank. They could go back to my website by clicking the back arrow. Is there a way that my client can still remain on website?
Thank you!
markustracy.com.
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I have switched the form thank you page settings from a blank redirect page to the standard message.

The issue should be fixed. You may submit the form again to confirm this.

Thank you!! You guys are AMAZING!!
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