@Krishna I already did export NODE_ENV=dev in each terminal before anything else.
As mentioned, SB mock and playground mock appear to work. I haven’t done anything with them but they look fine - ie the playground loads and clicking some of the APIs works.
The symptoms suggest to me that everything is working except that the website’s window is not internally hooked up properly inside the browser. My app javascript appears to be running without problems - just the browser’s website window not functioning as expected.