Ruthless mode vendor recipe doesn't seem to work with warstaves

The ruthless vendor ring recipe,

Magic Ring + Magic/Rare Weapon with Adds # to # (Fire/Cold/Lightning) Damage
Orb of Augmentation = Unidentified Magic Ring with +#% to (Fire/Cold/Lightning) Resistance

doesn't seem to work with warstaves. I've used it a bunch of times with other weapons, and tested it this time with both chaos and elemental ring inputs.

bugreport # 971,653,218

Warstave data:

Item Class: Warstaves
Rarity: Rare
Beast Gnarl
Maelström Staff
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Warstaff
Physical Damage: 71-147
Elemental Damage: 132-214 (augmented)
Critical Strike Chance: 6.80%
Attacks per Second: 1.25
Weapon Range: 13
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Requirements:
Level: 64
Str: 113
Int: 113
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Sockets: R
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Item Level: 73
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{ Implicit Modifier }
+25% Chance to Block Attack Damage while wielding a Staff (implicit)
(Warstaves are considered Staves) (implicit)
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{ Prefix Modifier "Weaponmaster's" (Tier: 1) — Attack, Gem }
+2 to Level of Socketed Melee Gems
{ Prefix Modifier "Polar" (Tier: 3) — Damage, Elemental, Cold, Attack }
Adds 132(99-136) to 214(200-232) Cold Damage
{ Suffix Modifier "of Conflagrating" (Tier: 1) — Damage, Elemental, Fire }
52(51-60)% increased Burning Damage
{ Suffix Modifier "of Static" (Tier: 5) — Damage, Elemental, Lightning }
10(8-12)% increased Lightning Damage

I think the issue might be with the Tier 3 cold damage mod "Polar." I can replicate this bug with the "Polar" mod on a Lion Sword or or Labrys.

EDIT: The recipe did work the with "Polar" mod on a One-Handed weapon. So the bug might be exclusive to the two-handed version of the mod.