I’m having the same problem. My height maps are in the same location as when I first created the tiled layers; when I click on reimport from the world browser, it does nothing. I tried importing the specific tile/layer and it says “filesize does not match…”
When I export the 1 layer, it gives me the weight map for the whole world rather than the tile/level. So perhaps I have to combine ALL tiles for a specific layer? I’d rather just reimport the whole thing, as that would be pretty tedious.