I'm running into a similar issue when deleting the first item in the list box control. The list is loaded during the first page_init subroutine and I'm trying to remove the first item in the list. I have the "AllowDelete" option set to true & the "ButtonSettings-ShowDelete" option set to true and I'm using the delete button provided by the control to remove the item. When I click the delete button, the item is removed, but as soon as I submit via a button control, I get the following error:
System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Any guidance would be greatly appreciated. If there's a need to use the track/commit changes with the built-in delete button control for the list box, could you possibly send me the necessary JS code to do so?