You tried to capture or act on text on the Chrome settings page or in the Web Store and Omni does absolutely nothing.
This is a browser-level restriction, not a bug and not a setting. Chrome forbids every extension from running on its own pages, which includes all chrome:// URLs such as Settings and History, the Chrome Web Store, the DevTools window, and about: pages. Nothing happens there because nothing is permitted to run there, for any extension.
There is no workaround. If a page you care about is not a Chrome internal page and Omni still does nothing, check that site access is granted in Settings, Overview, and check whether the site itself blocks extensions.