E.164 format support - contact_phone_edit.php (#1581)
The + prefix is being removed, this should be ignored for the very start of the string, resolution below.
Line 69.
Replace:
$phone_number = preg_replace('{\D}', '', $phone_number);
With:
$phone_number = preg_replace('{(?!^\+)[\D]}', '', $phone_number);