ReactJS chrome extension installed but not showing up

In chrome://extensions/ select Allow access to file URLs for the React Developer Tools extension, using v0.13.1 of React. I didn't need to add anything to my source code.

I was having this issue just now and to solve it I had to open dev tools -> click the gear icon on the top right of the dev tools window then in the far right column at the very bottom is a button that should say "restore defaults and reload" click that. I was not able to figure out the exact reason it was not appearing but it at least gets react debugging working again.

Just happened to me on Chrome 100. Reloading the page, reopening DevTools panel, toggling the extension on/off, restarting the browser and closing other app windows didn't help.

What fixed it for me was: CMD+SHIFT+P and selecting "Reload DevTools" from the command panel. For non-Macs it will probably be CTRL+SHIFT+P.