I had an issue where I downloaded Xcode 27 and every time Allow/Don't Allow showed for Claude Agent chat I got Apple beach ball and it froze. I oddly resolved it (with Claude advice) by resizing the Xcode pane to a smaller size - it seemed the wider UI was somehow the issue - possibly because it was in left pane before. If you resize Xcode pane and the Allow button is subsequently smaller - its working fine for me now. Not sure if same issue as you, but hopefully may help.