Hoppers into Chests (after minecart hoppers into hoppers)

screenshot in environment

another screenshot attached
world files attached

In attempting to make a smelter that simultaneously smelts 16 objects (kelp) wihtout the use of comparitors, I encountered a strange bug in which kelp was not fully entering a chest (it flickers in and out).

I suspect this has to do with splitting items up with 2 itterations of the hopper minecart, but I'm unsure.

Hopefully including the world files will make it easier to figgure out than my poor explanation.

 

Thanks,

Healex2