Cannot use Verglas in Elemental Weakness with Doedre's Undoing

Hello,

If you're using Doedre's Undoing lineage support with Elemental Weakness, you cannot slot in the gem Verglas, even though Elemental Weakness is a cold skill you cast yourself and becomes a damaging spell.

If you put in Decaying Hex, you can put in Verglas.

The intended behaviour should be that once Doedre's Undoing is slotted in, you can put Verglas in Elemental Weakness supports without needing to also put Decaying Hex.