I offer a file download with checkout via Paypal WPS.

During the last 4 days I it failed two times.

The first time, 4 days ago, the user had paid via Paypal and then did not receive his file. When I checked, then there was not even a user account for him in my system. So I thought that maybe Paypal did not correctly report to Moneyscripts.

However, today I had a case, in which the user paid via Paypal but then received no download link. No email, no file download link under "my files".

When I checked then I found that he had a user. But the user did not have the role "clients" (which it should have had), nor did it have access to the download. I did not find an order in the system. 

Today I had "Main Settings / Log Module Message to Database" turned on. So in theory I might even be able to troubleshoot that case a bit, but I have no clue what to look for.

Any idea what might go wrong here?