The X between boxes 7 and 8 is not the box 7 code. The box 7 code is a letter (other than X) or an number, or a combination of two letters/numbers. When the box 7 code is 7, some people get confused and do not recognized that 7 is the code. Code 7 means that the distribution was made after reaching age 59½.
An X on the Form 1099-R between boxes 7 and 8 indicates that the distribution is from a type of traditional IRA, not from a 401(k). If the box is marked on the Form 1099-R that you received from the payer, mark the IRA/SEP/SIMPLE box on TurboTax's form.
If you believe that the account is a 401(k), contact the account custodian for an explanation.