Why is the filter option grayed out?

Filters are only applied when stocks are being displayed in the table (with one exception, explained in the next paragraph). So if you have a parent item such as Portfolios, Indices, or Sectors selected in the Navigation panel, you will not be able to access the filter option in the column pull down menu. Any filters you have in place are not applied, but they have not been lost; they will be applied again whenever you are again looking at stocks.

Filters are not applied to any tickers in the Quotes Box. If you select ‘Quotes’ in the Navigation panel, the filter option will not be usable.

How do I filter the Table... I created a filter, and now...