Ionic-v5 debug in browser

Hi,
typescript source are missing on browser debug

Ionic:

   Ionic CLI                     : 5.4.16 (/usr/local/lib/node_modules/ionic)
   Ionic Framework               : @ionic/angular 4.11.10
   @angular-devkit/build-angular : 0.801.3
   @angular-devkit/schematics    : 8.1.3
   @angular/cli                  : 8.1.3
   @ionic/angular-toolkit        : 2.0.0

Cordova:

   Cordova CLI       : 9.0.0 (cordova-lib@9.0.1)
   Cordova Platforms : ios 5.1.1
   Cordova Plugins   : cordova-plugin-ionic-keyboard 2.2.0, cordova-plugin-ionic-webview 4.1.3, (and 5 other plugins)

ionic -v
5.4.16

in tsconfig.json:

"sourceMap": true,

any suggestion?

thanks in advance