The Invar Blend quest in chapter 2 cannot be completed because it wants Mekanism "Steel Dust" which has no recipe, and the Create mixer gives Thermal "Steel Blend".

This is 1.1.2. I assume the "fixed in dev" tag means you managed to reproduce it?

Edit: Confirmed 1.1.3 fixes it, thanks. :)

which version of the modpack?
This is the recipe in the current version 1.1.2

the create mixer gives Mekanism Steel Dust