All Volume Info outputs are 0 (color is default) even though my fluid fire simulation looks good

Hi. My fluid fire simulation looks good, but all the Volume Info node outputs are their defaults for every frame: Color is NodeSocketValue.default_value, Density, Flame and Temperature are all invariably 0. I want to use a Color Ramp to adjust the color from blue, yellow, orange, red, but there is no data coming out of the Volume Info node.
I have a Python script printing all these values to the console for every frame.
I have tried upgrading Blender (I’m at 4.2.3), reinstalling, and starting over from scratch.

I have tried debugging with ChatGPT and Copilot, and both referred me here.
Any suggestions?

Welcome!

isn’t the volume info node for volume objects, such as imported .VDB files?

Does it work if you create an attribute node and type in “flame”?