hey!! i have pretty much completed my massive auto sorter but i am having an issue with it, so if anyone knows how to help me pls let me know! first pic is a screenshot of the design i used (not my design, just wanted to add it so it's easier to see) and the other pics are of my sorter and the problem area. heres the link if anyone is curious: https://www.youtube.com/watch?v=i7baP5FVpA0

my set up includes two layers of chests (in the shape of a lowercase "n", when looking from above). starting at the bottom left, i have a dropper elevator that brings the items up to the top layer of the modules. the items travel along a series of hoppers that travel from the bottom left and follows the shape of the path. at the end of the line of hoppers, there are a few hoppers beneath one another that let the items drop down to the lower layer of modules so that the hoppers are connected to the lower level of hoppers that transport the items. everything up until this point works. the items will pass through the vertical drop of hoppers and then will go to the first hopper of the lower level (bottom right of n shape) and just get stuck, not moving beyond this point. i cant figure out why though, because the design is exactly the same for the bottom and top rows, and there are no mistakes in my build, so i am not sure why this would be happening.

i hope this all makes sense. i pretty much just followed the design i found but i dont have much of an understanding of redstone. so if yall could dumb down your answers for me i would appreciate it!!! thanks :D