Users dont get the file they paid for
Using Jamroom
Looking in your ACP you have may modules in there that I suspect are not being used. I turned off the "Proxima" set of modules which are for mobile app developers to use jamroom as a data storage system. It doesnt look like thats the goal of your site.
You have Genosis which is a family tree system and the old version of site builder.
Suggest a clean up to remove modules not being used.
When I ran a test from a live sever on jamroom hosting, the IPN notification
did come in from the sandbox.paypal.com system indicating communication.
08/17/16 06:48:07AM 173.0.82.126 jrPayPal: notified 7@site.com of pending eCheck
08/17/16 06:48:07AM 173.0.82.126 jrPayPal: processing incoming transaction: 63D31925HF4626017
Try turning the IPN settings at paypal.com to ON with the URL I gave you above and let me know its response.