What’s the problem?
Sometimes you may notice that even though the “Name/Full Name/Other Name” variable is present in the opt-in message for any widget connected with a “Checkbox” button type (such as “Button”, “Box”, “Modal”, etc.), the email sent to your subscribers does not include their name.
How do you view the messages in the process?

How does it reach your subscribers?

The reason this happens is that due to Facebook's restrictions, ManyChat variables only work in the opt-in messages when connected to the widget via the “Send to Messenger” button type.
How to troubleshoot
To resolve this issue, you can edit your opt-in message to look good without the username, or change the button type of the widget to “Send to Messenger”.