Bug? Lune not consuming stains anymore?

[RattyRyan]

Try as I must, I cannot seem to get Lune to consume stains anymore, even though I clearly have enough for an improved spell. The text stays greyed out, and the stains do not appear to be consumed. What gives? I'm in Act 2 right now, was working fine until yesterday, and I tried changing weapons but that didn't change anything.