Solution
When you try to install a product the second time using NIPM, it shows the 'No operation to be performed message' because the product is already installed. The additional packages listed the first time do not belong to the product. Showing those additional packages, the second time might give an illusion that the product is being installed even though it isn't, or that the installation failed the first time. So this is currently the expected behavior.
The additional packages can be installed from the PACKAGES tab or using the Install or remove related packages option present in for each product in the INSTALLED tab. Additional packages are fetched from ni.com so for completely offline systems, the two options above will not work directly. The workaround for offline systems is to first register the offline feed and then proceed with any of the two options.