Welcome e-mail being sent twice, despite default e-mail being disbaled

I have set up a notification for a user welcome e-mail using the wizard.

When a user signs up for the site, they correctly get sent my custom e-mail with their username and password reset link.

The trouble is, the default WordPress e-mail also sends. I have this e-mail disabled in the integrations page, so it should not send. In the debug page, it does not mention the default e-mail, but the custom one is there.