Do you sacrifice a guide voodoo to the lava? If you do- do you actually have the NPC to be killed- aka the guide? If he's not spawned in; the guide that is. You can't summon the Wall of Flesh.
Terraria Community Forums
Thee Pie Man
Mattix
What am I? He dies every time, but the wall doesn't spawn. I do sacrifice his voodoo doll in lava. I get the horrified debuff every time I enter hell. I've even made a thread about it in the PC bugs section.