Why isn't the portion of our medicare premium that's been taken out of my wife's SS benefit showing up on the (Michigan) state "Medical Insurance and HMO Premiums Paid"?

In the online version, you need to select the Homestead Credit and answer the questions.   One of the questions is Medical Insurance or HMO Premiums Reduce Household Resources.  It then shows Medical Insurance and HMO Premiums Paid and then will have an amount or $0.   It then has a box for you to fill in an amount of your Medical Portion of Auto Insurance Premiums.  Make sure that you have entered all of your medical premiums on Schedule A of the federal return.   If the Medical Insurance and HMO Premiums Paid is $0, I would go back to the federal and double-check they are shown on Schedule A and are in the correct spot.

In TurboTax Desktop you can go into Forms, go to the MI-1040 CR form and then add the amount to Line 31 if it did not calculate the amount.