May those elements are ‘invisble’ (visible=false)? I’m facing a similar issue since I’ve updated to 1.6 and XCUITest. The problem for me is that the DOM elements that has visible=false attribute can’t be extracted as WebElement, so I can’t perform any action on it.
My issue is documented at thead How to handle XCUITest 'visible' attribute? check it out may it’s the same cause.