TalentLMS lets you choose how a unit can be completed among three options: with a checkbox, with a question (1) or after a specified period of time.
When you choose the second option, your users must answer a question to complete the unit. If the answer is correct, then the unit is completed. So, a unit completion question exists only to serve that specific purpose, and it’s not recorded by the system or displayed in any of your reports.
A simple workaround for that is to add a one-question test after a unit, that users have to pass before they proceed.