In the Edit Employee window, select the Payroll Info tab and make sure to check if the Pay Frequency is correct.
Click on the Taxes button and review the Filing Status and Allowances in the Federal and State tabs. Make changes if necessary.
Hit the OK button twice.
Once done with the payroll update, you can revert the employee's paycheck to refresh the information and calculate the taxes. I've got this article for the steps: How to save or revert pending paychecks.
You can also check out these articles for reference on why taxes are not calculated: