I already reported that stone ovens despawn at restart. I'm getting a little jaded after losing another cooking pot, and a tripod. And stones don't grow on trees.
There should be a system that they don't despawn if they are within x metres of a building item (fence, tent etc). Stone fireplaces, and stone ovens are base features. Fireplaces (wood+kindling) are the disposable ones that should be removed at restart.