I figured it out but yes, I was confused about entering contributions to a Virginia 529 plan into my Virginia state return. I was operating under the incorrect assumption that the limit was $4000 per beneficiary instead of $4000 per account and therefore TurboTax wasn't handling it correctly.
Here are the relevant sections I found in the "VA529 Invest Program Description" document:
“Account” means the separate Invest529 account set up for each Portfolio by an Account Owner. Since each Account can have only one Portfolio, the same Account Owner may have multiple Accounts for the same Beneficiary in different Portfolios. Each investment by the same Account Owner will result in a separate Account as long as the Account Owner, the Beneficiary or the Portfolio is different. The same Account Owner may not establish multiple Accounts for the same Beneficiary in the same Portfolio.
Virginia Tax Deduction. Invest529 Account Owners who file a Virginia state individual income tax return can deduct Invest529 Contributions from their Virginia taxable income. The deduction is limited to $4,000 per taxable year per Virginia529 account (each separate account held within Invest529, Prepaid529, CollegeAmerica and CollegeWealth), or the amount contributed to each Virginia529 account during the year, whichever is less, with unlimited carry forward until the full amount of the Contributions has been deducted.
