There is nothing that needs to be fixed. The calculation is correct. MAGI is calculated differently for different purposes. There are over a dozen different definitions of MAGI, depending on what it's being used for. For the deductions on Schedule 1-A, including the deduction for seniors, MAGI is Adjusted Gross Income (AGI) plus the Foreign Earned Income Exclusion, Foreign Housing Exclusion or Deduction, and excluded income from sources in Puerto Rico, Guam, American Samoa, and the Northern Mariana Islands. Tax-exempt interest is not added. For most people MAGI will be the same as AGI.
