Since the Creator's Update in Windows 10, I have been unable to search items in the Control Panel from the Start Menu. I waited for a long time in the hopes that it would resolve itself. It has not. I have followed the instructions here: What do I have to index in order to search the Windows Control Panel (in Win10)? and on many other related posts because they seemed to have a similar issue. These solutions have not resolved the issue, however. I believe Windows 10 Creator's Update removed Control Panel's items from being indexed.
Note that, regarding Solution 2 in the top answer to my link, my directory %LOCALAPPDATA%\Packages\windows.immersivecontrolpanel_cw5n1h2txyewy\LocalState is completely empty.
I do not have multiple languages enabled, so that shouldn't be an issue. This de-indexing has occurred on both my Windows 10 PCs that updated to the Creator's Update. I can still search for Control Panel, but the individual items inside are not available (such as Programs & Features). This is very problematic as Settings has far fewer options than Control Panel.