WHMCS never generates duplicate invoices for the same service on the same due date, so if a new invoice is required after deleting an invoice you would need to manually move the Next Due Date forward/back by 1 day.Doing this should get invoice generation going again.
To correct this change the Next Due Date to the date of the client's next payment via their Products/Services tab.
Secondly ensure the Tax Exempt checkbox is unticked on the client's Profile tab.
This may have been ticked by a member of staff or our EU VAT Invoicing Addon Module (if activated).
Therefore two tax rules would be required, one for "TX" and another for "Texas".
Any changes will be applied to subsequent invoices, existing invoices will not be changed.