Yup that's the thing which I hated. I remember now.
So going from the books it looks like invisibility has to be messing with species directly not just destroying images.
Now my revised model of an invisibility spell functions by both destroying the image and shuttling all of the iconic species across the volume of the invisible object where light can't carry them. I still don't necessarily have an image that Discern the Images of Truth and Falsehood's function of "tell whether an image has been created or altered" can act upon.
Is there an issue with my revised model? Or have we taken it back to YMMV (even if were really look hard at the texts and try to come up with an answer rather than thinking about what's best for our table)?