If you cannot batch process and only the first image selected is processed, it is becuase "Edit All Selected Variants" has been turned off. You can enable this feature againfrom the Edit Menu or via the tool bar icon pictured below (the icon is Orange when enabled).
Note that this feature also affects applying styles and presets to batches of images, Applying copied adjustments to batches of images and batch renaming as well.
The reason the Capture One allows it to be disabled is that when it is on ratings and color tags will be applied to all selected. In some situations that might not be the desired behavior.