I opened my store http://snakebitecoffee.co not so long ago and have had orders, and continue to get orders with no problems.
However for the last 8 weeks I have had policy violation of "User cannot purchase" in google merchant centre. I have checked all the policies and to my knowledge am not contradiction any. I have had others look at it and google themselves aren't much use.
When you click on the checkout button, it takes just a little or around 3 seconds to be directed to the checkout. This can result in a user cannot purchase. However I have not seen this warning on a 3 second checkout.
But did see it on a 10 second checkout. Just to eliminate this potential, I recommend improving the speed. This can be caused by an app.
However I did spot an issue, in the cart you say, before taxes and shipping. Everywhere except US and Canada, all prices must be inc vat. So make sure you remove this message in the cart. And submit prices inc vat.
For the rest I cant spot anything.
Contact Google Merchant Center, and kindly ask them for examples of issues.