AWS SES Open tracking not working

Hi,

I have sending html transactional emails to my customers. For this I have enabled SNS topic with an email subscription to monitor open tracking. But it doesn't seem to be working at all. Maybe I am missing something, but I don't see that clearly.

I have sent a sample email (html) to myself to test this, but no open metrics are recorded.
Message ID 010001682c9803f3-1b6a5f21-267c-45be-98cd-2b96b4b35556-000000@email.amazonses.com

In SES Configuration Set, I have following settings:

SNS Name:Open
Event types:Open
Domain for Open tracking:Amazon SES Default Domain
Enabled:True
Topic:open

Can someone please guide me here?