Vanilla Minecraft v.1.16.5, Singleplayer
I needed to make a 1 wide dropper randomising system, to add to a random shulker box dispenser, so built the design shown in Image 1. The hopper is empty, acting as an input to the system and each dropper starts with 3 empty shulker boxes. [The initial design had an output dropper and a comparator as the input but once the thing started breaking I turned it into a loop and used a lever for testing]
The design worked as planned and I incorporated it into the item feed as shown in Image 2, however now 4 of the bottom droppers were locking and not firing, breaking the system.
Confused, as the systems were identical, I built it a few more times (as in Image 3) and discovered the problem was location based, originally I assumed it had to be crossing a chunk border to work properly, wasn't sure why but was the only difference between the 3 systems. (Green wool = works, Red wool = not working)
Curious, I expanded my testing out as shown in Image 4. Green wool is where the system worked fine and red wool was where a few of the droppers locked up (which droppers locked up, varied between location) I am yet to rotate or change the number of droppers for the design until I can figure out why the system is location dependant.
My question is, why do these droppers behave differently dependant on their location in the world? Thank you.
I haven't included a world download as I feel the attached images allow for easy duplication of this problem. (Camera is facing East in all the screenshots)