@Aliasz 

Hi,
On the Tapo app>camera's Device Settings>Detection>Area Intrusion Detection page, please check if the camera's activity zone is set correctly. 
You can go to the Tapo app>Cameras tab, tap the Play icon on the Tapo C310, tap Manage on it once the camera plays, then go to the Area Intrusion Detection page to ensure the camera's Live View and activity zone are up-to-date.

On the Area Intrusion Detection>Schedule page, please ensure this feature is turned on during the time you want.

Please send me the MAC address of your camera via private message if the settings are correct.

Best Regards

  @Aliasz 

Hi,
Can you describe the usage scenario you want to achieve? 
On the Detection & Alerts page, I see that AI Detection(including Person Detection) and Line-Crossing Detection are turned on, which means if a person moves in front of the camera, you will receive person-detected notifications.
Best Regards

Hi  @Aliasz 
Reset the camera to default settings and reconfigure it may be useless for this issue. Please turn off the AI Detection and Line-Crossing Detection feature on your Tapo app, ensure the notification for the Area Intrusion Detection is turned on, then try to enter the activity zone you set for the Area Intrusion Detection, record the time and date when you enter the activity zone, and check if you can receive the relevant notification on your phone or on the Tapo app>Home page>Message page.
If not, please send me the recorded time, date, and your time zone for analysis.

@Regal  On the camera's Device Settings>Detection page, did you enable the Area Intrusion Detection only? Can you send me a picture of the camera's Detection page?

Best Regards

  @Aliasz 

Hi,
Glad to hear that you have solved the issue, and thank you very much for the solution sharing.
Best Regards