Iron Furnaces don't save the items that are in it when saving and reloading a world. I created a issue on there github repo but they said it was most likely being caused by another mod.

Yes, it is the same with me : the upgrade in the furnaces of @ironfunaces just dispawn when i get back in my map

Seems to be reported on the IronFurnaces repository as well: Qelifern/IronFurnaces#76

Ok, thank you.

Supposedly fixed in IronFurnaces version 3.1.1 according to mod repo. Have not verified (version in ATM7 modpack has not yet been updated)