This is usually because you either still need to enter more itemized deductions to have an amount over the Standard deduction, or your refund amount has maxed out based on your tax withholding.
What's my standard
deduction?
https://ttlc.intuit.com/replies/4208574
How does the itemized
deduction differ from the standard deduction?
https://ttlc.intuit.com/replies/3302313
