May I ask if you have ever been able to get your UI to correctly scale to users changing the HUD Scale option in the game menu?
My UI is all scalable between different resolutions, but once the HUD Scale is set in the Fortnite settings it breaks.
Essentially you can recreate this by taking your UI widget and going into the top level parent and increasing the scaling to 1.25x1.25. The widgets seem to treat this as a resolution change but the available screen area indicated by the scaler arrow thing does not change so objects that are anchored to the far top/bottom corners on each side will be pushed out of the UI display area, and likewise on downsize scaling it pushes everything into a small box in the middle.
Example. The coffee cup image is using 1.0, 1.0 alignment, and is anchored to the bottom right corner anchor of this canvas.
When this scaling happens the available screen size doesn’t change but the anchors move, so now the corner anchors exist off of the edge of the viewable canvas space.