Oh boy, looks like something's setting game variable 239 way too high. That's be the Windup multiplier, which is used to calculate the amount that certain Modifiers affect Windup. It should not be in the 100s. I'll look through and figure out where it's being set.
EDIT: Found it! Should have a fix out in a bit.
I specifically made Guardbreak + Split Strike more expensive because of how strong their synergy is. It's the same trick Hedge Knights have, but a Split Strike Mix can have 50 damage per hit and an element attached to it.