The picture is a simple automation setup, in which it uses a temp sensor and a redstone cable w/ 2 redstone torches to invert their signal (yes it’s unnecessary).
On testing I found that, when the sensor goes on (meaning torches goes of so hopper starts dropping), the one that is closer only drop once, while the further ones will drop as long as signal is off.
It is fixable by just simply change the number of drops, still it is an interesting “bug” that I found. Maybe it isn’t a bug and I am missing something?
