There’s a style of Frame called DropShadow which has inherent padding. For instance, here is a GUIObject parented to a DropShadow style Frame at Position=UDim2(0,0,0,0) and with Size=UDim2(1,0,0,35):
Despite having a horizontal scale of 1 and being positioned in the top-left corner, it’s offset a little because of the Frame’s padding. However, when a UI constraint determines the size/position of an element, it doesn’t take this padding into account. Here is the same frame when positioned by a UIListLayout:
Upon further testing, it seems this bug may extend past UI constraints. Without any UI Constraints, Insert two or more items into a DropShadow Frame and delete one of them – the other items will update their positions to ignore padding.
This bug appears to have been fixed. I think I fixed it while working on UIPadding, as I can no longer reproduce any issues using constraints in DropShadow Frames.