Ionic browser + Onesignal web push

Hi everybody,
I use ionic 4 firstly.
I have a problem on Onesignal web push. it works well on my android application. But this is not the case on the browser after following the documentation
My browser application have no bug, but Onesignal notification don’t work

I want to use onesignal web push in my ionic browser application.

isUsingSubscriptionWorkaround() cannot be called until OneSignal.config

I have the same issue @elierak26. Please reply if you have found solution to this. Appreciate your support. Thanks