Cannot cremate corpse (need material)

I have a crematorium that is configured to forever burn corpses. I have a pile of dead bodies nearby, but when i try to prioritize work in there, I only get:

Cannot cremate corpse (need material)

I am pretty sure that colonists could burn corpses before, but then apparently they stopped for unknown reason.

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Figured that out, seems it's a bug with the error description. It says "needs material", but in practice I have built a wall and a door in such a way that it was inaccessible, so that's what fixed it for me, built the door at the correct spot :)