I spent rather a long time narrowing down the problem. Looks as the upgrade of an Angular project does break the debugging capabilities
Works under @angular/cli1.0.6 using angular @firstname.lastname@example.org
Fails to debug under @angular/cli1.1.2 using angular @email@example.com
I downloaded as well WebStorm-172.2953.12.exe. This on showed a crash in the WebPack loading (and I used the feedback to report).
Illegal char <:> at index 40: C:/js_prj/AngularTraining/Test2\/webpack:/C:/js_prj/AngularTraining/Test2/~/@angular/core/@angular/core.es5.js
I hope my summary makes sense. For the moment I switched back to the older version of angular.