Setup and details never end. Going through again this evening store settings, I decided to sign up and take advantage of bitpay.
Saving my store settings I discovered a leading and trailing \ being added to the url and title in the message to the payee about being redirected to bitpay, not to worry, it is completely safe. At first I thought it was something 'code-like' that I knew nothing about. After the 3rd save I noticed an equal # of the \ had now appeared.
Delete all, Save again. One more \ added.
I think we got a bug here.