Hi @Alex Sleiborg,
Welcome to the Community and thanks for posting! I’d be happy to assist with your question regarding adding a phone number to email templates!
Did you initiate a preview from the "Email Templates" tab by any chance? If so, that would be the reason why the properties aren't appearing. You can use the template created in a Campaign or Flow email, then you'll be able to accurately preview as a specific profile. You can find more context here: Previewing dynamic content.
Ideally, a customer has already had their phone number attached to their profile. If this is the case, then I would recommend using the {{ person|lookup:'phone_number }}
instead of just {{ phone_number }}
. Alternatively, try {{ person.phone_number }} as well. Our guide on using template tags and variable syntax goes over other tags you can add to customize your emails as well!
Hope this helped :)
Alex