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 https://documentation.onesignal.com/docs/web-push-custom-code-setup
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