Why is the IRR value different in Holdings Detail vs. Risk and Reward?

In Portfolio Analytics there are two tabs available that show the Internal Rate of Return (IRR): the Risk vs. Reward table and the Holdings Detail table.

The IRR calculation is very complex and generally the IRR numbers in these two tables will not agree. The reason is they are computed two different ways. The Risk and Reward table contains the accurate IRR value for the portfolio, where as the the summary IRR value in Holdings Detail is more like a spreadsheet average of IRR for the individual holdings.

What do the “Adjusted...