Does the app not work in low light?

Hi, I've really enjoyed using the app. I'm starting to get into night photography and noticed that when I change film with different ISO, the readings for the measurements don't change. I've attached two photos, one with it set to Colorplus 200 and the other set to Portra 800. https://imgur.com/a/MUmOQmz

I'm trying to avoid buying a light meter, so it would be great if it worked in low light!

Your help would be much appreciated!