With update 6.0, the ability to use dusts in certain furnaces (futurepack and Thermal Expansion) has been removed while retaining the recipe in JEI. Testing was done with iron dusts but all dusts usable in a Mekanism processing setup is affected (personally tested 4 of them). The only current fix is to run them through an alloy smelter at the moment.
With update 6.0, the ability to use dusts in certain furnaces (futurepack and Thermal Expansion) has been removed while retaining the recipe in JEI. Testing was done with iron dusts but all dusts usable in a Mekanism processing setup is affected (personally tested 4 of them). The only current fix is to run them through an alloy smelter at the moment.