NavigationSplitView sidebar toggle button missing on iPadOS 26 beta 3

I just upgraded to Xcode 26 beta 3 and when I run my iPad app the toggle sidebar button is no longer visible when I set the column visibility to .detailOnly. I don't apply any modifiers to my NavigationSplitView. It looks like this.

NavigationSplitView(columnVisibility: $sceneModel.columnVisibility) {
    GPSidebarView(appModels: self.appModels())                
} detail: {
    GPRootContentViewIOS26(appModels: self.appModels())
}

I also don't do .toolbar(removing: .sidebarToggle) anywhere in my code.

Yesterday when I had Xcode 26 beta 2 the toggle sidebar button was there on my detail only view. I am trying to figure out if there is something that I did to break this and after looking at my git history the only thing I can see is that I upgraded Xcode 26.

Here is what I get when I set the column visibility to .detailOnly.

Then here is what I get when I set the column visibility to .doubleColumn.