Why does switching from fire to smoke result in an incorrect real time simulation?

If you switch an Smoke Flow and change it’s type, the resulting simulation is incorrect. Free All Bake does not delete the bake from the blendcache folder.

The way to start a correct simulation is to Bake or to delete the blendcache folder which will result in a correct real time simulation. Deleting the contents of the folder or modifying a invalidating property still results in an invalid simulation.

Is this a bug or am I misunderstanding something?