I used 34 Glass Needles on my Titan's ACD/o Feedback Fence and never got an Intellect / Discipline roll. It only ever rolled Discipline / Strength, Intellect / Strength, or just Strength. According to the Armory here on the website, the ACD/0 Feedback Fence can roll with 30 - 60 of all 3 stats. It's unique perk doesn't provide you with an extra melee charge such as the Sealed Ahamkara's Grasps for the Hunter; it is confusing why it is (or at least it seems to be) locked to Strength on every possible roll.