Freeform Question - Pick One - Saying "Invalid Answer"

Hey everyone, I've got a problem with the freeform "Pick One" question in Storyline 360. 

What's happening:

I have .pngs uploaded to be the choices, everything is set up correctly in the form view with the four images as options and image 4 selected as the correct answer. When I test the program in Storyline and in Review, I get the following error: Invalid Answer - You must complete the question before submitting.

Backstory

This only starts happening on scenes 10-17 in the file. The scenes before that I was using an image grouped with a text box as the answers. I'm not having any issues with that.

I copy-pasted the scene as they are all the same and then switch out the content for the assessment. 

I saved those groups as an image so that it would be faster for me to switch images out for the rest of the assessments as I built them. I'm not sure why this would cause a problem since they are just .png files still. 

 

What I've tried

I tried adding in a png file to scene 9 (which works) and scene 10 (which doesn't work) to see if it was an issue with the groups I turned into images. The unrelated png file works fine in scene 9 and doesn't work in scene 10.

 I tried creating a brand new question in scene 10, but still had the same problem. 

Copy-pasted the question from scene 10 to scene 9 to see if it would work, it didn't work. 

 

Thanks for any help or suggestions. The file is included below.