Hi Chris,
Thank you for the question.

In case of checkbox, radio and select box, you need to specify the label and values in the corresponding boxes. You haven’t specified that.

Please follow these steps:-

1. Delete the old checkbox field
2. Select the checkbox from the deopdown field types
3. Since we have only one option here, we don’t need comma separated value
In the Options field, Please put yes
In the Options Lables field, Please put Yes

The values ‘yes’ and ‘Yes’ are without quotes.

and save.

4. In case you need multiple options in future, Please put the values separated by comma in Options( e.g. one, 2, three etc)
and corresponding labels ( e.g One, Two, Three items etc) in the Options Label field.

Please give it a try and let me know if it works or not?

Regards
Brajesh