Trouble Adding Contact for Drop In

[tmallardi]

I'm trying to setup and Echo Show 10 for an elderly parent.

I've created a new Amazon account.

I've registered the device to the new account.

I've downloaded the Alexa app on iPhone.

Logged in to IOS Alexa app with new account

I went into settings and enabled Communications,

I've enabled Drop In
 

However, when I attempt to add a contact whose cell number is confirmed to have an Amazon account, the Enable Drop In option does not appear under Permissions.
I know for a fact that the contact I'm trying to add, has a phone number registered on Amazon.

Not sure what step I'm missing...

Any advice would be greatly appreciated.