When I import subjects, why don't they appear in the list of subjects?

For imported subjects Categories used in a hierarchical list to correlate and organize information.Subjects are used in the subject tree to organize products, sales literature, and knowledge base articles. to be visible, the import source file must contain a column that maps to the Feature Mask attribute. The Feature Mask attribute determines whether the subject will be displayed in the subject tree. If Feature Mask is set to 1, the subject will be displayed. If it is empty or set to 0, the subject will not be displayed.

To build the subject hierarchy in the subject tree, you map the column in the source file that contains the title of the parent subject to the Parent Subject attribute. If no parent subject is provided, the subject will appear at the top level of the hierarchy.