Did you make entries on federal Schedule A for health insurance premiums (in addition to the 8962/PTC form)?
Missouri picks this up and adds it to the Medical Worksheet.
In the image above, there is a pre-filled in $7,000. $4,000 came from the 8962 (ACA insurance), and $3,000 was entered into federal Schedule A as health insurance premiums.
What additional health insurance premiums are you wanting to add?