Custom validation rule not working

[clff]

I have 2 inputs which together create a country code + a phone number.

I created a custom validation rule which compares the 2 strings with a regex and returns true if it's a valid phone number.

The problem is, that the validation doesn't update, even if I enter a correct phone number, it doesn't update to approve the validation.

You can see a codesandbox by clicking here

I'd appreciate any help, thanks.