I had the same problem. The basis for my IRA was on both the IRA Information Worksheet and the Form 8606 for tax year 2012. For tax year 2013 the basis was not transferred with the other tax data from the 2012 return. Therefore none of the basis was carried forward to any other future tax years.
For tax year 2019 I needed to withdraw an RMD so had to enter the IRA basis as shown on the 2012 Form 8606 onto the 2019 IRA Information Worksheet in Part II Line 12. This basis transfers to the Form 8606 Lne 2. This can only be done using the TurboTax desktop editions in Forms mode. Then clicking on Open Form and entering ira information in the search box.
Fortunately I had not entered any IRA contributions either deductible on nondeductible nor make any withdrawals in the years after 2012 so may basis was easily entered.
