Automation not triggering for all email addresses when form is filled out

I am reusing a few automations created last year for an annual program that is soon to begin.

I created a new form, however, and replaced the trigger in the automations to reflect the new form submission.

There are 2 automations:
a) An automation that sends a webhook to Zapier to give the contact access to a course in kajabi.
b) An automation that sends a welcome email immediately, and starting November 1st will send daily emails.

We’re finding that not all email addresses testing the whole process are working. We have set it up so that it runs multiple times if people submit their email more than once.

Any clue what could be happening?

Im not sure about for this scenario, but I setup an automation and no emails were being sent, I failed to first add them to any list before attempting to trigger the email. It won’t send automations if they are not part of a list.