Check your bell settings for that channel and see if you've opted-in to receive all notifications? You may be on the default setting, which is to receive notifications occasionally. Here's a guide to help check that plus your app and device level settings: https://goo.gl/giVA8o
Thanks for letting us know. Could you try uninstalling the app updates, restart your device and reinstall the updates to see if that fixes the issue? Keep us posted.