Sometimes this message appears when our system takes a few minutes longer to generate an award than the "Exam passed" message takes to appear. I've confirmed on the backend that we have awarded you a certificate, could you please refresh the page to populate the certificate?
If you continue to have this problem, I recommend you get in touch with HubSpot Technical Support, as support is included in your subscription and they can provide real-time assistance for this matter, where you can share screenshots and more information about it.