Unity UI Sprites/Gradient Material Draws Over my UI

I'm running into an issue in Unity 2018.4 where my slider bar (using a slick Image that has a gradient material) is rendering over every UI element leading to issues as shown below:



Any ideas how to get this to work? Everything is on Z = 0 (nothing that changing the Z value helped any). Seems like a basic thing that Unity should support, so I'm kind of at a loss.

EDIT: I changed it to a gradient image, so that works. But I'm still curious about the material