Sadly, when testing out the payload is different. In the sample JSON we see that appId, objectId, subscriptionId, eventId are number. If you click test, and hubspot send payload - all fields arrive as strings which might be ok for some loose typed languages, but not for strict typed.
And the actual webhook events send payloads as in example json. So the "Test" button functionality should be fixed, and it should send payload as it is described
Thanks for your patience here; I've just heard back from my team that a fix has been rolled out for this. The test webhook payload should now match the actual payload sent exactly (aside from the fact that it's test data). Let me know if you have any other questions here!
I can reproduce what you're talking about; let me take this to my team so that we can take a closer look. I'll reach back out in this thread when I have more information.