select all in listgrid in Selenium

Hi I'm running into some problems with existing selenium testcases. Since upgrading to SC 9.1 From March 18, the following line now fails. It cannot find the select all checkmark when a listgrid's selectionAppearance is "checkbox". Can you please verify? I used AutoTest in the js console to make sure the locator has not changed and it produces the same locator that we currently have.

selenium.click("scLocator=//ListGrid[ID=\"page$content$$content$codeTableField$cwFullLi st\"]/header/headerButton[fieldName=_checkboxField]/valueicon"