Esse erro aparece no console da aplicação, o que pode estar causando esse Timeout?
DevTools failed to load source map: Could not load content for http://localhost:4200/runtime.js.map: Load canceled due to load timeout
DevTools failed to load source map: Could not load content for http://localhost:4200/polyfills.js.map: Load canceled due to load timeout
DevTools failed to load source map: Could not load content for http://localhost:4200/styles.js.map: Load canceled due to load timeout
DevTools failed to load source map: Could not load content for http://localhost:4200/vendor.js.map: Load canceled due to load timeout
DevTools failed to load source map: Could not load content for http://localhost:4200/main.js.map: Load canceled due to load timeout