The "Prior Year Roth Conversions and Distributions" has three input fields:

• Basis in conversion - that is the basis before the conversion
  
• Taxable amount of conversion - the amount you paid taxes in that year
  
• Taxable amount of distribution - that is the distribution in that year
  

For the problem in question, the "Basis in conversion" and "Taxable amount of distribution" are both zeros for both years 2005 and 2016, only the "Taxable amount of conversion" needs to be filled out which are 10,000 and 20,000 in original problem, or 13,000 and 17,000 in my modification. This will produce the expected result and the worksheet make sense, which I will attach below. The worksheet shows how form 8606 line 1 is derived, it is based form 8606 line 23 adjusted by the prior year conversions.