Hello,
I have not spent much time on your VI to analyze it in detail. However, before I can answer your question, I'm wondering if there is any need for attribute nodes to be inside the 'for loop' for what you are doing? I observed that the last symbol is getting set if you move 'ItemSyms' attribute node to out side the for loop, and connect the output of shift register to it.
I'm not sure why it does so, because I have not spent much time on your VI. I hope this helps. If not let me know I will look into it detail.