Members not being activated after payment

I have read through several support posts on this topic, but none that really helped.

We are using Paypal express to process payments. When a new user registers and pays, they begin to be redirected back to the correct page - but then are taken to the Protected page, because for some reason their membership is not being activated. If I look under Transactions, it is showing no transactions. So I assume this is an issue of Paypal telling the site that payment was made so that membership can be activated.

In Paypal, auto-return is turned on, Payment Data Transfer is turned on, but then under IPN settings, I think this might be where our issue lies, but I don't know what to do about it. We are also using an Events Manager plugin so that people can pay to register for events, and it requires that the Notification URL be set to: - which I assume is maybe screwing up the payment notification for Membership? Does that field need to be blank for Membership IPNs to work? Or does it have to be something else? I am not sure how to work it if two different functions of the site need two different notification URLS.

Any help would be greatly appreciated as my client is currently having to manually activate every membership.