Strange behaviour when building a mesh tile that would melt

Seen something like this before once... decided that materials delivered for building melted before constructionn finished

I agree with Fluon, it happens all the time with ice tempshift plates for example. The difference is that it usually holds less material, not more 

Also noticed that if the material does not melt before construction finished, it ends up exchanging heat twice, once when material is delivered, and once more after construction is finished, deleting a lot of heat. But maybe that is another bug.