I have been testing our store via the PayPal sandbox option and thus far everything has worked perfectly.

The only thing I am not seeing is the IPN link back to the store after the payment has been verified.

So, I follow the process:

1) Place an order in the cart.
2) Checkout, which directs me to the PayPal Sandbox login page.
3) Login with my pre-configured SandBox "buyer" account.
4) Complete the payment.
5) Get the payment confirmation screen within the PayPal Sandbox for the buyer.
6) Click the "Return to ..." link to return to the store confirmation page, where I see my order number and the display order button-- with a note that says that the payment is waiting on verification and that I will be notified when the payment is verified.
7) Login to the PayPal SandBox with the preconfigured "seller" ID, then go to the order detail and click the "Accept" link down at the bottom to simulate the payment verification step.
8) Go back to the store page-- where I still see the order status as "Awaiting Payment".

So, I assume that this stage of the IPN is not working for whatever reason.  I have the IPN enabled on my "live" PayPal account (with the Seller ID)-- but didn't see a separate section from within the PayPal sandbox account where I can enable IPN there, so I'm assuming IPN is automatically enabled by default within the SandBox?  I use the same login ID for both the SandBox account and the normal PayPal account, but am not sure where the disconnect is.

As a final bit of background info-- I currently have the Store Admin settings set with the Unique Seller ID from my "live" account and with the PayPal ID field set as the preconfigured "seller ID" within my SandBox account.

Perhaps I just need to set up a new PayPal SandBox primary account that does NOT match my live account.  Either way, I appreciate this great module and anticipate being able to complete this project once I clear this final hurdle.