This glitch is very similar to the usual krissures glitch where:
"If the player dies near Krissures and uses a Touchstone, Life Giving Amulet, Meat Effigy or another method of resurrection, the Krissure will sometimes get stuck in the erupting state, but no longer allow the player to cook Food."- DS wiki.
The issue here is that each time you exit/re-enter the volcano, some of the krissure may get stuck in the erupting state. So overtime you end up with a bunch of erupting krissure providing light all day long, yet you can't cook food on it.
Unsure. May be related to re-entering volcano.