Field objects are field elements that are represented in the Object Manager (which means that they have a position and orientation). These objects can be manipulated manually in the Viewport and must be placed into a Field list in order to take effect - working with Child objects in the Object Manager doesn’t work.
When a Field object is created outside of a Field list (e.g., via the main menu), the Field will automatically be placed in the Field list of the element used with this Field, e.g., an Effector or Point Selection tag.
Note also that Fields will be displayed with a reduced number of settings when selected in the Field list - this is done to save space. All existing settings will be displayed in the Object Manager when a Field is selected.