Thanks for looking at it again. I could of probably made it a bit more obvious what the issue was, Sorry.

The thing that makes me think this is a bug is that the stack inserter will keep picking up items when going from one belt to another, Even if the belt has mixed stacks. Which is not what matches when going from a belt to an assembler.

I guess to clarify. The issue is that the stack inserter will ...

When having a mixed stack belt it is possible for the stack inserter placing items into a container such as an assembler to deadlock. The inserter is stuck attempting to pickup more items and never returns to functioning. Broken.mp4

This caused me a few issues when I finally upgraded to using ...