Can't find aggregation bug

Hi all!

I wrote a class progress log with some built in stats: 279Online Progress Log • Activity Builder by Desmos

Every other screen is a “Class Summary Screen” which aggregates data and displays it for the class. This is a screenshot from a currently running “log”, and what it is supposed to look like:
unnamed (3)

However, one of my classes looks like this:

I have figured out what’s wrong, I think: it works as soon ANYONE enters any numerical value in cell 5,2 (ONLY that cell fixes it) on the individual screen (like so):

What I don’t understand yet is WHY…

Thanks all for taking a look!

Did you find the bug? I copied two of the slides into this activity here, but was unable to replicate the bug, everything seemed like it worked for me.

Thanks for looking! No, I haven’t found it. Here’s a deeper look. Is this not what is happening for you?