The bug I mentioned relates to where the repeating code is placed, your issue now relates to the name of the button and the trigger code:
Change this code:
// WA DataAssist Multiple Updates
if (isset($_POST["button_<?php echo $RepeatSelectionCounter_1; ?>"])) // Trigger
{
to
// WA DataAssist Multiple Updates
if (isset($_POST["button)) // Trigger
{
and this code:
<td><input type="submit" name="button_<?php echo $RepeatSelectionCounter_1; ?>" id="button_<?php echo $RepeatSelectionCounter_1; ?>" value="Submit" /></td>
to
<td><input type="submit" name="button" id="button" value="Submit" /></td>
and you should be good to go