TextMeshPro's Shader & Timelines

Maybe this has been asked a bunch of times already - didn't see it.
I'm using Unity 2019.2.12f1...
Simple scene - TMP object in scene, and an empty object w/ a Timeline (playable) on it. I drag and drop the TMP onto the timeline and create an animation track....
I press record on the TMP object, then I get a stack of errors in the console:



and, I cannot expand or open the TMP shader variables panel. it's stuck closed.
Is this a known thing? How else would I animate the shader variables on a TMP object's shader? In particular, this shader is supposed to be a dissolve shader, not the normal one that is on the TMP. But the error happens for both.