GuiMLTextCtrl Text cut off on left during game update

I'm using a GuiMLTextCtrl. The text written to it during game start-up shows up fine:


The text written to it while the game is running cuts off at the left:


The same function is writing the text in both cases, concatenating the elements of a string array then sending the whole group to the GuiMLTextCtrl. Here's the relevant code (shortened because it concatenates a lot of variables):

function UpdateTextLog(%stringToEnter)
{
   for (%i = 5; %i > -1; %i--)
   {
      
      $chatLog[%i] = $chatLog[%i-1];
   }
   
   $chatLog[0] = %stringToEnter;
   DrawTextLog();
}

function DrawTextLog()
{
   GUIChatLog.setText($chatLog[0] NL $chatLog[1] NL $chatLog[2] NL $chatLog[3] NL $chatLog[4] NL $chatLog[5]);
   GUIChatLog.forceReflow();
}

Anyone know how to fix this? Thanks!