u/GlobalisedEnchilada

I've started the game on Xbox recently. Began in the desert biome. Very simple initial setup, miner pushing out ore 30/m, smelter pushing out ingots at 30/m. I have a constructor producing iron plates. It takes in at 30/m and pushes out plates at 20/m, straight into storage.

So the flow should be smooth, 30 ingots out and 30 ingots being consumed, per minute. But the belt into constructor keeps stopping and starting. It looks like there is a backup, but why ?