Why is the pop-up notification no longer displaying?

Hello,
Sorry for the delay.

1. I think you were able to figure that out because I can see the notification now. But If I’m wrong please let me know

2. There is one line on your CSS that is hiding the notification. This is the one:
.added_to_cart.wc-forward{ display:none }

You can try to find it and remove it, or you can add one CSS line to your Customizer > Additional CSS, trying to cancel it, like:
.added_to_cart.wc-forward{ display:inline !important }

If you can’t do it I can try to do it for you. Just let me know 😉