When I go to make my order, it does appear in the back end as Store Sales, but when I get to the checkout on the front end, click on Pay Now with PayPal or Pay Later with PP Credit, than I get the message that the session has ended from PayPal’s end. So we’re not sure it’s the plugins fault or PayPal.
We have tested in our demo sites, its working fine with our sandbox PayPal account.
It may be problem with your PayPal account. Kindly contact PayPal for this issue
They can help you to fix the problem.