That's unusual, but likely related to floating-point precision. I'd suggest playing with the code inside UIAnchor, on lines 215 and 232. I'd also suggest making sure that your UI has no XY rotation on any of the elements (Z rotation is fine), and that Z position on all elements is zero. I'm also not clear on why your top bar disappears when it gets behind the window. You said you're using 3.0.4, and 3.0.4 enforces the draw order based on depth, not Z.