I presume that you have created a static asset group under Configuration\Asset Groups. Such a group cannot add assets on it's own, as it can only be used to manually select and group assets.
As you want to automatically group assets based on IP address, we would recommend to make use of the IP Location groups on the same page. Here you will be able to fill in the IP address range, in your case 10.10.1.0 - 10.10.1.254. This will automatically give these assets the correct IP Location, whenever they are discovered with an IP within that range.
More information on grouping assets can be found in
this knowledge base article.