Hello!

1. Do you mean when you open UNAMessenger desktop app? If so then please be sure that you are using the latest version https://github.com/unaio/una-desktop-app/releases/tag/1.1.0

2. Do you mean push notifications in mobile app on mobile devise? Do you get push notifications in web version from any of your browser's on PC (Note: web push notifications doesn't work on IOS and Mac devices)?

Also if you set OneSignal settings in studio -> settings -> push notifications area, you also need to enable option in Jot Messenger settings -  "Enable OneSignal Push Notifications (If global site's push notification options are set, they will be used for messenger)", then messenger will use site's onesignal settings to send push notifications.