Cannot animate fire emission area in Blender 2.82

Hello, I’d like to use the impressive new Mantaflow simulator to animate a marshmallow catching on fire. I’d like one spot of the marshmallow to catch fire, with the fire slowly spreading out to engulf the entire marshmallow. I’ve created a texture which starts as completely black, then develops an area of white which spreads over the whole marshmallow. In theory, I should be able to apply this texture to the flow object (the marshmallow) to control where the fire is emitted, but the fire simulation seems to ignore the animation of my texture map, and pick only one frame to use as the map for where to emit fire. It doesn’t even seem to be consistent about what frame it picks. Sometimes most of the marshmallow will go up in flames, other times only a small spot. Do animated image texture maps not work properly with Mantaflow to control flow?

In theory, I could use an animated procedural texture to do this, but since nodes aren’t available for textures used outside materials, I can’t adequately control how a procedural texture spreads across the whole object.

Files:

MarshmallowFireTest.blend (1.7 MB)