Why do I see legend items for features which are not exported in the map?

The exported legend items are related to the visible layers in the map. If your map extent shows a map area where no features of your visible layers are available, the export of the related feature layout items depends on the configuration of the legend element in the legend layout template.

You can update this configuration in ArcGIS Pro: select the legend element and navigate to '> legend item properties > legend items > show properties > feature display options > only show features visible in the map extent'.

You have two options for 'only show features visible in the map extent':

1. Checked: the engine only exports legend items of visible layers with visible features in the map extent. When choosing this option, the print might take more time since an additional calculation is necessary, but you will get the most compact form of legend items.
2. Not checked: the engine exports legend items of visible layers no matter if the features are visible in the map extent or not. When choosing this option, the print is faster, but you will potentially see legend items not relevant in your map extent.