Unless I missed some undocumented change, dusts seem to be broken as they smelt into nuggets instead of ingots.

Edit: Even JEI shows this:

Wierd.. As stated at https://github.com/aidancbrady/Mekanism/blob/1.11/src/main/java/mekanism/common/Mekanism.java#L827 it should be a ingot..

I tested all possible dusts and they all smelt into nuggets.
Were you able to replicate this?

I'm currently not able to start a dev environment. I will let you know when I'm home and tested this.

Looks like you have some additional mods who are changing the minecraft smelting. Mekanism uses the vanilla smelting. My dusts are smelting just fine to ingots.

Seems like BetterWithMods somehow managed to slip into my test instance of Minecraft.
Resolved: NOTABUG

(You can close your own issues ;) )

How much I hate a wonky internet connection...