Extrude - Non-Parallel Faces

The selected faces must be parallel to each other. Select faces separately or try using Up to face.

Use Up to face if you want to recognize by selecting end faces.

When you select multiple faces but do not select Up to face, FeatureWorks first checks whether the faces are parallel. If they are parallel, FeatureWorks then checks whether they are coplanar (see Extrude - Non-Coplanar Faces).