With the beta feature "New Source Browser" enabled, and the repository is being watched, commit notification is not being sent out.
However, after disabling this feature, and navigating to Repository Overview >> Click watch the repository, and select "Commits", you will be able to receive the commits notification. (After doing this, enabling the New Source Browser and you will be able to receive commit notification)
- Navigate to Bitbucket Settings >> Labs
- Disable the feature "New Source Browser experience
- Refresh the repository and click "Overview" tab
- Click the drop down arrow next to the "eye" logo on the right hand side of the page
- Select "Watch This Repository" and check the boxes for the features you would like to receive notifications for.