Electronic – Logisim – wire holds value ‘e’ when zoomed out, but not when zoomed in

I'm trying to make a multiplier in logisim. This is a full picture of my schematic:

As you can see, there is an 'e' coming out of my 'XXXXX-XXX00' adder. But, when I look at the schematic for 'XXXXX-XXX00' adder, this is what I see:

Why am I getting 'e' outside of the adder but not inside of it? How can I get it to output the 'right' value?

Also – this one wire isn't the only place I'm getting these 'e's. Depending on the values of the 2 numbers I'm multiplying, I'll get these 'e's in all sorts of fun places.

Thanks for the help!