invalid number when calling mobiles for CCP in the UK

Hi, I'm in the UK and using Amazon Connect CCP. I am unable to make calls to mobiles using the E.164 method. (ex +4407xxx xxxxxx), getting an error message:

Initialization Failed.

Try fixing your connection by logging out, and then logging on again. If you need help, contact your administrator.

This affects mobile number only and not landlines. I can make calls to landlines.

CCP security profile CCP: Outbound is added to the Agent making the call enhance the ability to call landlines '

Please see attached.