very odd redstone bug

when using a Synchronized furnace array one random furnace does not turn on for no reason. this only happens in the snapshots iv tested it

i expected all the furnaces to turn on at the same time

all but one turned on

Steps to Reproduce:
1. download the world from link below,
tutorial video https://www.youtube.com/watch?v=acKnjrKSqzI

2. play in latest snapshots ad but a smeltable stack of items into top left chest

3.watch furnaces one random one will not turn on every time

4. create a new copy of the same world and try without snapshot

p.s. this is not an issue with building it wrong, this is a bug that probly has to do with hoppers and redstone ticks