There are a couple of checkpoints:

1. Did you create an endpoint in Live mode, and use its Signing secret respectively?

2. If you look at https://dashboard.stripe.com/test/webhooks do you see your Live mode events? They should appear it regardless of whether they are sent to your endpoints or not.

   1. If they do, then look inside to see if they were sent and what your server responded.

3. Otherwise, you can look at your PaymentIntent on Dashboard, scroll down to the "Events and logs" and check if you see events there.