I tried to get this to work with the island mods, but even when I changed the fill_ratio to 0.1 for minetest.register_decoration where decoration = "magma:volcano", I still didn't see any volcanos.
They are very rare, otherwise this may be a problem caused by the Islands mod.
I will take a look at it, but may not be able to fix anything for a week as I am out of town.
I tried to get this to work with the island mods, but even when I changed the fill_ratio to 0.1 for minetest.register_decoration where decoration = "magma:volcano", I still didn't see any volcanos.
They are very rare, otherwise this may be a problem caused by the Islands mod. I will take a look at it, but may not be able to fix anything for a week as I am out of town.