Why is my Ohio joint filing credit missing?

All of those count except social security  (social security income is deducted on the OH return).

To qualify for this credit, you and your spouse must each have at least $500 of qualifying income and jointly file your return. "Qualifying income" is any amount included in Ohio adjusted gross income, other than the following:
●Interest;
●Dividends and distributions;
●Capital gains; AND
●Rents and royalties

Then, any Ohio schedule A deductions (like excess  medical expenses) or Federal adjustments (the most common being an IRA deduction) must be subtracted from the qualifying income. If either spouse has less than $500 net, you will not qualify for the Joint filing credit. Take a look at the allocation form that TT does, it should show these adjustments.

In the "forms mode", look at the Joint Filing Credit Allocation Worksheet.

Did you have any of the following:

-medical expenses exceeding 7-1/2% of AGI

-IRA deductions

-student loan interest deduction

-1/2 self employment tax deduction

-educator expense deduction

-alimony deduction

-out of state military pay 

-any other adjustments on Ohio sch A

-Small Business Deduction

If so, and those items were deducted from your qualifying income, would that income be reduced to less than $500?