Hi,

If your email campaign in Odoo 16 is not tracking opened or clicked emails from Gmail, there could be several reasons for this issue. Here are some troubleshooting steps to help you identify and resolve the problem:

1)Check Configuration Settings:

Make sure your email server settings in Odoo are correctly configured. Ensure that you have set up the SMTP server, credentials, and other email settings correctly.

2)Check Email Sending Logs:

Review the email sending logs in Odoo to see if there are any errors or issues when sending emails. This can provide insight into why tracking might not be working.Settings -> Technical -> Emails

3)Check the trigger time that given to the next child activity
In each activity you should need to provide the triggering time of that activity, so confirm the trigger time that you provided 

Hope it helps