In @ionic/angular@5.0.0, when a modal layer is opened by modalController, and another modal layer is opened in it, and then the latter is closed, there will be a problem: a translucent mask layer will be displayed on the screen (backdrop). Upgraded to @ionic/angular@5.1.1, this problem was solved.
But in @ionic/angular@5.4.4(and @ionic/angular@5.1.1 ) there is another new problem: when opening another modal in one modal and closing the latter, ionic will push the componennt page of the second Modal into the navigation stack, the browser address has also changed. In the end, I can only solve it with the following code temporarily:
this.modalControll.dismiss().then(()=> this.navController.pop());