I'm running react 16.12.0, react-dom 16.12.0 and scheduler 0.19.1.
On a production build, when I view Profiler tab it says:
Profiling not supported.
Profiling support requires either a development or production-profiling build of React v16.5+.
Learn more at fb.me/react-profiling.
And on a development build, I get this popup when I try to access React DevTools. The console doesn't show the Profiler tab either.
