After “pay now” there is no forwarding

Hello,
I have integrated your plugin since a few days in WooCommerce. As far as everything goes until I noticed a bug.

I use WooFunnels in the checkout and here comes when paying an error. It is not forwarded after clicking on “pay now”!

There is then an order confirmation but the customer is not forwarded, for example, to Paypal. Have now used various Paypal plugins but the just does not work.

Here is a link where you can test the checkout:
https://webzeugx.de/checkouts/checkout/

As soon as I deactivate your plugin, then it works without probleme.
What could be the problem? I have now spent several hours to find the problem but it is not possible!

Greetings,
Michael