Minecraft 1.8.9
Forge 11.15.1.1732
Blood Magic version 1.8.9-2.0.0-15
JEI Version: 1.8.9_2.25.7.145

Hovering over the progress bar for the Hellfire Forge recipes displays a Format error message for the Demon will cost:
"Format Error: Minimum: %,d Will
Format Error: Drained: %,d Will"

Right, those are floats, not ints. Oops

All better (test recipe)