Even I have same problem.
I have 3 options. First with Paypal seems to work properly with sandbox.
In second option we have wire-transfer details and third is to decide later. In last two cases upon ‘Submit’ we are getting an error “Error! Something went wrong during checkout and payment couldn’t be approved.”
I wonder why should this error come for 2nd and 3rd option where there is no PayPal payment integration?
How to solve this issue?