I had the same problem and reported it to the author. I sent the paypal transaction ID and the order number and email from their website. All I got as a response was that they couldn’t find a match for the paypal ID.
Obviously, I’ve never had that issue with paypal. And I definitely don’t buy the author’s claims that they cannot reproduce the problem. Clearly, multiple users are reporting the same issues.
Worked great for half a year. Now it no longer works. I found a different solution as well, outside of the app. No need for a fix for me, either.
I certainly won’t be renewing my license or purchasing another for other sites.