I have setup Zapier with QF and the tests from Zapier all work.
However, I have setup some zaps based on QF Invoice creation to send an email. After creating a number of invoices in QF (and sending them) and viewing the zap task history on Zapier (after a couple of hours), nothing is showing.
If you go to Account Settings >> 3rd Party Integration >> API, and then select Webhooks Dashboard, you should be able to see any notifications (and their timestamp) when we’re sending the data to Zapier.