UMG Update Dynamic Material?

I have an UMG set up that has a circular bar which is an “Image” containing a material that changes based on a parameter I control from my HUD. If I draw the material directly through the HUD Blueprint I can see the bar changing, but through my UMG HUD, the bar remains static.
Do I have to update my UMG’s Image every tick or something? If so, how do I do that?

Event Tick is how the do it in the quick start guide.