Without looking at the code it's impossible to tell, but the numbers 10 and 13 offer a definite clue - these are the ASCII values for line feed and carriage return. I'm guessing that your code somehow took the index and converted it into a string (probably using Byte Array to String) and put it in one of the columns (I'm guessing you wanted an index display). The rest of the chars there have no visible representation, but those two will manifest as new lines.
If that's the case, the solution would be to use something like Number to Decimal String to do the conversion.
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