As you can see, here it shows the count of how many delivered and what percent failed.
But on the other hand, on opening this the table is empty and there are no logs. I would like to investigate the reason of failed webhook deliveries, but I’m unable to do so.
There may be some delay in those logs appearing, which I’ve experienced previously, so they might come through in time. It does state the logs are an approximation of your deliveries so not everything might be available. 
Do you have any logs or metrics from your own application?
Thanks for pointing this out! While webhooks were sent correctly, we unfortunately don’t have log data for webhooks that occurred between Jan 21 and Jan 24. More recent logs should be surfacing, although, as @JordanFinners pointed out, this may not be an exhaustive list.
After like many days, I see logs appearing normally now.
The day I posted the query above, It had been several days since I implemented the Webhook.
We have metrics from our API Gateway where we see incoming request, so we know request are coming.
Anyways, seems it normal now.
