How can I filter out values on Timeline view?

When I create a filter all the dropdown values still appear. I am using the Timeline view to show a roadmap of upcoming projects. There are 40 projects listed but only 20 have been assigned to an area. I have a list of the 12 areas who could be assigned a project, currently on about 6 areas are assigned a project. The timeline view shows all areas, even those without a project. I would like for the timeline to only show areas that are assigned a project. I created a filter to show areas that are not blank. This works on the Grid view. It doesn't on the Timeline view see screenshot for example. Allocation and Assets shouldn't appear since those groups have not been assigned a project. They are listed in the drop down as a value to be selected.

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