Once the loaders have been placed - if you click on a loader to open the inventory screen, a red indicator appears (red bar) in sort of the middle of the loader that is permanently stuck in that location of the world. Removing/re-adding loaders does not fix it - in fact, nothing can get rid of the red bar.

In short; something happens when you click on a loader to open its inventory, causing a red bar to appear in the world.

Can you upload an image to a site like imgur? I can't seem to recreate this issue on my end

I created an Issue on GitHub with an image.

Alright, I left a reply on github.