I'm on a Mac and have recently uninstalled and reinstalled all my CC apps as to the latest version.
Now Extension Manager isn't showing any products. How can I get it to register the software? It's all in the applications folder on my computer. I've restarted everything.
Extensions have metadata which defines the versions of CC which they are compatible with. Perhaps your extensions are not marked as working with the version of Adobe product you are using.
You can also manually place the extensions in the magic folder where the Adobe product looks for them and they will appear.