
As you can see in the image above, The Stack inserter is set to stack size 5 but it outputs a stack of 4 items onto the belt. In this case it has a filter set by a control signal. I expected it to put 5 items on the belt in a stack of 4 and a stack of 1 and it took a while to realize this was the issue.
I have also attached a save with this build on Vulcanus.
I tired searching for this, i did not find a relevant bug post, if this is expected behavior sorry to waste your time, as always everyone on the team has made an amazing game thank you.