A customer object isn't created for non-recurring payments unless you configure CBSubs Stripe to do so. More than likely those payments don't have a customer object associated with them so they'll just show email address.

First and Last Name are always sent as part of the credit card details. Enabling customer objects for single payments will have no impact on past purchases only new purchases. Click the payment and you should see they've a customer object attached to it, which should have their name in that customer object. I've no idea why Stripe decides to display email address instead of name sometimes.