Line 2 of your 2015 Form 8606 should have shown the $5,500 from line 14 of your 2014 Form 8606. The error in not showing that will have continued to propagate forward.
TurboTax losing your basis information can result from not transferring in a previous year's tax file that recorded you traditional IRA basis or by inadvertently telling TurboTax that you did not make nondeductible traditional IRA contributions. If you tell TurboTax that you did not make any nondeductible contributions, TurboTax will silently delete any basis carried in from your prior-year tax return.
