not opening tab on ipad

[d3NNEb]

using firebase auth js per https://firebase.google.com/docs/auth/web/cordova

code

        var provider = new firebase.auth.GoogleAuthProvider();

        firebase.auth().signInWithRedirect(provider).then(function () {
            return firebase.auth().getRedirectResult();
        }).then((result) => {
            ...
        }).catch((error) => {
            ...
        });

on iphone (simulator AND device), browsertab opens for oauth signin
on ipad (simulator AND device), browsertab does not open

any ideas?