I had the same problem. Got with my company and they showed me that they did everything correctly and all the legal jargan fot them paying me using a "Common agent" for two different legal entities. My company showed that they didn't owe me the FICA overpayment back but the IRS did. There is a way to claim this as a credit on your tax return. But you have to do it manually within the turbotax forms; turbotax won't do it for you. TurboTax does recognize the overpayment of the FICA and suggests that you need to get the money back from your employer which is incorrect for me as I did work for two different legal entities.
The fix within turbotax is to go into the Forms (top right) and go to the 1040/1040SR Wks (worksheets). Near the bottom is "Part II Other Payments and Refundable Credits". The first section there is for this exact issue titled "Excess Social Security and Tier I RRTA Tax Withheld Smart Worksheet". Enter your overpayment amount in box "A" and it will reduce you tax payment; or increase your refund by this amount.
