When doing meter billing from customer contracts and there does not appear to be any invoices generated, please check what the setup is for Bill Only Validate Readings in the Workflow (contract) module.
If it is enabled, you need to validate the readings first which can normally be done by using the Trial Run functionality of the billing module involved (e.g. Consolidated Billing Batch, Contract Billing Batch).
When the meter is validated, you will see that in the readings as shown below by the check mark under the Is Validated column:
If you don’t need to validate, disable the parameter in the Workflow (contracts)