It may be something with the way you initialize the shift register. I built a similar loop with a random number generator rather than file input. To initialize the shift register I created a constant and it is different from the one on your image.
You've done a few things wrong. Instead of reading the files with each iteration of the loop, read them once outside. You should just wire the array of paths to the for loop with autoindexing turned on. Then you eliminate the array size and wiring that to the iteration terminal. You don't have autoindexing turned on ofr the output of the for loop so all you get out is the result from the last read.