Multiple email notifications since upgrade 4.0

I just updated to 4.0 yesterday, I also use the ebay WP Lister Pro and had an order overnight. I received a couple messages from the buyer that I sent out about 20 emails telling him his order is complete. He sent me a screen shot of his email list and they are there and the times show he received them over a couple hour period. I disables notifications on my end.

Have there been any other problems with this? Because it could be on his end, but I’m unsure how to tell that either. His was the only order, is there a way for me to place a test order and see if it does it to me.

https://wordpress.org/plugins/woocommerce-admin-bar-addition/