Hello there, GHC.
I appreciate you for giving us some insights about the troubleshooting steps you did so far. I'd like this to be taken care of.
Since I want to make sure you'll be routed to the right support that can help you with processing customer payments, I suggest you reach out to our QuckBooks Merchant Support Team. They can pull up your account in a secure environment and verify the status of payments for you.
Just in case you'd love to know more about processing payments for credit card transactions, feel free to check out this link: Process a payment in Merchant Service Center.
I'm always around if you have any other concerns about payment processing. Just make sure to leave a comment below and I'll get back to you.