Lock icon won't go away after quiz completion

Hello Garrett!

The lock icon appears in the menu when the Navigation Restrictions are set to either Locked or Restricted. Here's an article which explains which explains the behavior in greater detail: 

Storyline 360: How to Restrict or Lock Navigation 

Since the behavior that you are seeing affects quizzes specifically, try enabling the 'Show Slide Draw Questions' in the menu to see which questions in your course has a lock icon that will not go away.

Once the Slide Draw is shown in the menu, check to see that each question is being presented to the learner. If some questions are being skipped, check your slide triggers to see if there are any triggers that may be preventing certain questions from being answered. 

Let me know if this works for you!