Axios doesn't post on cold start

I have a function that is triggered when an SES email is received. It’s based on this serverless example:

I have added an extra step that uses Axios to post data to a webhook. The problem is that the post never happens on a cold start. I can trigger it again immediately after the first try and it completes successfully. There are no errors reported on the first run.

Any tips or gotchas with something like this?

Thanks!