About lazy loading, I don’t use it right now because including the components result in my project of many duplication of their codes in the bundles.
But there is hope, therefore I just list here some issue/pull request I found related to this subject:
Webpack issue: https://github.com/webpack/webpack/issues/3981
Webpack related PR: https://github.com/webpack/webpack/pull/4416 and https://github.com/webpack/webpack/pull/4255
Angule CLI issue: https://github.com/angular/angular-cli/issues/6204 and https://github.com/angular/angular-cli/issues/2771
Ionic app-script issue: https://github.com/driftyco/ionic-app-scripts/issues/867