I have a few hearths lined up end to end. Their bounding boxes overlap so that there is continuous fire, The ground slopes slightly along the lengthwise dimension of the hearths. I've used stone floor and wall blocks to level the slope. The hearths at the top of the slope seem to work fine. For the portions of the hearths above the slope, when I or any other creature stands or walks on the stone edges or the hearth, the hearth takes damage. This only happens when the hearth is lit. The hearth reports "10" in white about every second, or more often if I move. There is also the noise of rock hitting rock.