Monster Spawner fire particles remain when the spawner block is removed using /fill

What I expected to happen was...:
I did /fill <coords> air to remove a bunch of monster spawners. The spawners should have been gone completely. But... |
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What actually happened was...:
The spawners were gone, but the fire particles they normally produce just stayed there, floating in midair!

Steps to Reproduce:
1. Do /fill ~ ~ ~ ~ ~ ~ mob_spawner 0 replace

{EntityId:Enderman}

2. Do /fill <spawner coordinates> air
3. The spawner is removed. Now, watch those floating fire particles...