I have created a lambda function and added an API gateway. I have copy-pasted the endpoint in the webhook, but for some reason the lambda function is not getting triggered.
Hi @Sudh-f714, thanks for reaching out. We're working with Engineering and will be in touch in the next day or two. We appreciate your patience during this time 
HI @Sudh-f714,
I hope you are doing well.
On my end, I tried to simulate the issue. I verified that webhook does not work if API Gateway uses GET method. I tested the same lambda call using API Gateway's POST method and it worked fine. When you create an API in API gateway, it is important that you select the POST method.
I hope this was helpful. Feel free to contact us if you have any further questions.