Solved
We entered the state we live in, as well as Puerto Rico, but everything else was various. There are complicated computations provided by the Brokerage additional information sheet, listing every single state and the percentage of dividends that would be tax-exempt in those states. company is Pershing, LLC
Are you sure it's not for some 1099-INT or 1099-DIV form you've entered, for which you have not yet broken down the $$ amounts? (Box 8 is for the exempt $$ on a 1099-INT, and on a 1099-DIV, box 12 is used)
Make sure......on the follow-up page, you entered those $$ as follows (for an NC resident):

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