Signs of mites but no mites to be found. What's the matter?

[Wyorp Rock]

I will try that. The Eglu Cube is a little over 2x3x3. I'm not great at math but it seems like it's more like the 1-2 sq ft than the 4 that you're talking about. The thing that makes me think that it's not just them pecking each other though is the grey film over their litter. I was reading that that is a sure sign of mites, but I don't know where they could be living!!

3X3 would be 9sqft. you have 5 hens so that is 1.8sqft per hen. Is the nesting area on the outside or is that included inside that space?

You mention a grey film on the litter. In your photos I do see some new feathers coming in, could the grey pieces be keratin sheaths that are dropping off the new feather growth? If you have a photo of that film it might be helpful.