As you can see in the picture you can see visible white blocky corners that ruin the UI corner effects. I know that UI corner wont work on scrolling frames but if a scrolling frame’s background is transparent and is a child of a frame that UI corner does effect, why doesnt it all work out?
If I understand your problem right, you could try to use a CanvasGroup instead of a Frame (The name one named “Frame” and parent of your UICorner). CanvasGroup affect all their children, so it should round up the corners of your ScrollingFrame.
This is intended behavior. It doesn’t make sense one instance will affect every one of its descendants when there’s a class designed specifically for that (CanvasGroups).
Put the UI Corner inside the actual scrolling frame. It’s treated as an actual frame, hence the name
