Notifications are On, but some Android phones pause them in the background to save battery — so they only arrive after you open the app. To always receive them, turn off Battery Optimization for Vignyapan:

1. Open your phone Settings → Apps → Vignyapan
2. Tap Battery
3. Select Unrestricted (turn Battery Optimization off)
4. Reopen Vignyapan

Steps may vary slightly by phone (Samsung: Battery → Unrestricted & turn off “Put app to sleep”).