I suspect that you are forgetting about the Self Employed Health Insurance deduction. That reduces your AGI.
For a simplified explanation, let's say your profit from the business is $10,000 and you paid a total of $12,000 for health insurance. The $10,000 is first added to your AGI, but then the Self Employed Health Insurance deduction gives a deduction of $10,000 which lowers your AGI (the $12,000 is limited to the $10,000 profit of the business).
Does that sound like what may be happening?
If you print out your tax return, you can see the business profit on Line 3 of Schedule 1, and the Self Employed Health Insurance deduction on Line 16 of Schedule 1.
