Whittle targeting highest mod tier on fracture item?

Hey all, I know how exactly whittles work or don't is maybe a bit fuzzy but I'm thoroughly stumped by this one. My neck has, among other things, a t4 spell damage roll, t3 all melee skills (fractured), and t8 dexterity. The spell damage is the lowest modifiable tier on the item but the whittle wants to target the dexterity. I assume it normally targets based on tier which would be the + gem levels mod but that's fractured.

The alternative theory I've heard is that whittles target the mod with the lowest ilvl requirement (which would be super opaque if intended), but even if that's the case this still shouldn't be happening. T8 dexterity (based on craftofexile) requires ilvl 74, far higher than the ilvl 50 for t4 spell damage.

I'm at a loss here, is this a bug with fractures and whittles?