Can't get SetMaterial via blueprint to work on sprites

I have a character blueprint with a flipbook-sprite component on it. It is the event script of MyCharacter blueprint. When I change the material in component view it works just fine, but when I try to do the same thing in game via blueprint, it does not work. What I want to do: The sprite is unlit most of the time (defaultspritematerial), but in certain areas I want lighting to affect it by changing the material to (defultlitspritematerial)

Showing that the flipbook component has a material on it. Changing it to lit here works fine.
ScreenHunter_345 Oct. 28 18.08.jpg

Pressing x does run the event and the log does print. Material on the other hand stays the same. Does the fact that it is a flipbook have anything to do with it? I can change on sprites, but not on flipbooks unless I change it manually in the editor.

Any help would be greatly appreciated!