Ice Not Melting In Tamed Metal Volcano Steam

disclaimer: i am in no way afflicted with klei.
this is not really a bug. no heat will flow when a object has less than 1g, the reasons for this are 2 fold:
1. this reduces some performance requirement as all object with less than 1g are ignored
2. if you have a tile with high thermal mass (ie 3000kg of steel at 3600C) and it is touching something like 0.5g of oxygen gas. when heat is conducted to the oxygen while the oxygen temperature will change by a lot, the temperature change of the steel will be too low for the memory precision to be able to record it. so the gas will get hotter but the steel will not get colder thus creating a lot of heat. if that was the case you could construct something like a abysallite melter with that setup that need no external heat and is pumping out molten tungsten at 3500C
 

items < 1g don't exchange heat

Ah, that would be a great reason!   I have some trophy ice in my 300F steam then.

 

Thanks for the answer.