Onesignal opt-in popup Cordova/Ionic Android fails -

unfortunately have problem onesignal ionic.

what working?:
- ios , android devices accept push messages fine
- users show on onesignal admin panel fine
- can manually opt-in , opt-out (using window.plugins.onesignal.setsubscription(true/false);)
- on ios receive popup asking me opt-in push messages.

not working:
- not receive popup on android devices asking me opt-in. users automatically opt-in ;-) spent few hours reading stackoverflow, onesignal user manuals no solution provided.

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my app.js

document.addeventlistener('deviceready', function () {   // enable debug issues.   // window.plugins.onesignal.setloglevel({loglevel: 4, visuallevel: 4});    var notificationopenedcallback = function(jsondata) {     console.log('didreceiveremotenotificationcallback: ' + json.stringify(jsondata));   };    window.plugins.onesignal.init("11111111-1111-1111-1111-111111111111",                                  {googleprojectnumber: "1111111111111"},                                  notificationopenedcallback);    // show alert box if notification comes in when user in app.   window.plugins.onesignal.enableinappalertnotification(true); }, false); 

i installed "onesignal-cordova-plugin

android users automatically opted onesignal push notifications. if ask permission first can call onesignal.setsubscription(false); after onesignal.init(...) keep them being opted in automatically. display own in app prompt call onesignal.setsubscription(true); if accept.