Issues with quizzes

It sounds like you might be copying and pasting elements onto standard graded-question slides. If that is the case, those pasted elements would not be recognized as part of the question/responses. 

However, you could convert the "previously designed slides that currently have no functionality assigned" into Freeform questions. That would let you indicate what elements to use for grading the question.

Here's more info about Freeforms: Storyline 360: Converting an Existing Slide to a Freeform Interaction | Articulate - Community 

And if I'm completely misunderstanding what you're asking, I'll second what SamHill​ said: It'll be easier to help if there's more information to work with—and, ideally, a .story file to look at. 

FYI, here are the best practices for uploading a .story file:

• Only include slides that are related to the problem.
• Be sure objects, layers, motion paths, and variables have meaningful names.
• If there is proprietary content, replace or delete it. For example, replace proprietary text with “ipsum lorem” text.