This happens when you have chosen the "text-only "option in the campaign settings.
When you choose this option, open and link tracking are disabled, so you won't know who has opened your emails.
In the "Analytics" tab, you'll see that the "Opened" and "Clicked" analytics are grayed out.
Don't worry about this. However, if you want to regain the ability to see who has opened or clicked, simply uncheck the "send emails as text-only (no HTML)" option and click the "Save" button.
💡 Using text-only significantly boosts your email delivery rate.
If your emails are landing in spam folders using certain email addresses,
switching to text-only can help ensure they arrive in the inbox mots
of the time.