animated uv's with bone driven controller not working in unreal 5

I have a simple material + texture and params for u and v plugged in. Altering those params clearly moves the texture as expected. And yet if I name either param in bone driven controllers (using a bone’s trans X / Z animtion), nothing happens. I’ve checked the animation which is fine. This used to work fine in unreal 4. What am I forgetting?..

The animation curve for the material?
Check this. Seems better written than the old docs for a change:
https://dev.epicgames.com/documentation/en-us/unreal-engine/animation-curves-in-unreal-engine