Options Assign objects to the devices of the view... and Detach objects from the devices of the view... are always active in the context menu if Automatically load amount and items is selected under Menu Bar > Misc > Settings > Views and Searches > Page Behavior > When opening a view result... . If one of the other parameters is chosen, the above options will only be active after clicking a button Load devices (or Search for hits > Load devices) in the content panel of the view. See also Views and Searches.