The extra parentheses remove the errors for me. But there are issues with anchoring in editor mode, which means I can no longer edit the anchors visually in Editor with 4.5.5p3. All of the anchored items snap to their target's center, and I no longer see the pink/purple outline of the UIRoot (I'm not sure if that outline is for the root or panel as I'm just using a single panel)
But once I hit play they seem to anchor fine and I see the pink outline again.