I have three "real" portfolios and two "virtual" ones. The latter are marked as "Not included in total holdings".
I use My Holdings to view the aggregate holdings across my portfolios (which is an excellent feature). However, for symbols that appear in both "real" and "virtual" portfolios, the values displayed in My Holdings include both kinds of holdings, so the results are affected by the portfolios marked as "Not included in total holdings". This is not what I would expect.
This seems like a bug and limits the usefulness of the My Holdings feature. Please fix it or add a way to exclude portfolios from this view.