Thanks so much for the screenshot, @Andreia1! 
This does look like a bug. Please try to disable all email notifications, close the Organization settings, then reopen the settings and enable the notifications again.
Please also note notifications are only sent out for actions and changes performed by others; you will not receive a notification for actions you perform yourself.
If the problem persists after following the steps, I’d recommend you to contact our Support Team (Asana Support - Help Center • Asana) and provide the following information:
- Example URL of a task for which you should have received a notification but you didn’t.
- Confirm if you are collaborating with more people in your Personal Projects space.
Lastly, I see you are currently working on a Personal Projects space. If you’d like to have access to more features in Asana, I’d recommend you to create a Workspace. Have a look at this thread for more information: Should I use Workspaces or Organisation? - #2 by James_Carl
I hope this helps! Let me know if you have any questions 