This may not be exactly similar to what this post is… but someone who landed here like I did may be experiencing something similar to my problem. I had an Array where and I wanted to get random item from it. So I put in random integer in range 0 min and Length -1 as maximum, but I kept getting an error. For me it turned out that my “empty” array wasn’t empty, it had blank for index 0. So I had to use the Clear array node in the other blue print where I was resetting array values. So my empty was actually empty and all indexes would come out as true.