If it came from the manufacturer it's a spiff. It's not business income, and it's not wages. It doesn't matter if they call it a commission or something else.
You entered the 1099-MISC incorrectly. It should not be linked to Schedule C. Delete the 1099-MISC. If the 1099-MISC is the only income on the Schedule C, delete the Schedule C also.
To delete the 1099-MISC, go back to the 1099-MISC Summary and click the Delete button or trash can for the 1099-MISC that you want to delete. The simplest way to get to the 1099-MISC Summary is to type 1099-misc in the Search box, then click the link that says "Jump to 1099-misc."
After you delete the 1099-MISC, enter it again. I assume the payment is in box 3. After you enter the 1099-MISC, continue through the questions until you get to the screen that says "Does one of these uncommon situations apply?" On that screen, select "This was a manufacturer's incentive payment" and click Continue. ("Manufacturer's incentive payment" is the IRS term for a spiff.) The income will be reported as other income on Schedule 1 line 8z.
