With a recent update, WebEx notifications settings are changed from the default to Direct messages and @mentions to me, resulting in it showing the new messages notification on the WebEx icon for the direct posts and direct mentions only.
To keep receiving notifications on all posts to the WebEx Teams:
- click on the Gear icon in WebEx.
- go to Notifications.
- then go to Messages and set the notification to All messages (default).
- Click Save.