iPhone in-app browser freezes after send auth request to keycloak server

static keycloakConfigLoginSwitch = {
 'url': ENV.URL.authServer,
 'realm': ENV.INSTANCE.realm,
 'clientId': 'theClientId'
};

static initUsingLoginSwitch(): Promise<any> {
 let keycloakAuth: Keycloak.KeycloakInstance = Keycloak(KeycloakService.keycloakConfigLoginSwitch);
 KeycloakService.auth.loggedIn = false;

return new Promise((resolve, reject) => {
 keycloakAuth.init(\{ onLoad: 'login-required', checkLoginIframe: false })
 .success((loggedIn: boolean) => {
 // IN APP BROWSER WINDOW FREEZES
 if (loggedIn) {
 // next steps
 } else {
 reject('Keycloak did not authenticate client');
 }
 })
 .error((error) => {
 reject(error);
 });
 });