Having the same issue:
My Blizzard and Twitch accounts have been connected for a long time, and I’ve claimed several other WoW items, such as Cotton Candy Grrgle. I completed 4 hours of watching Hazelnutty and Esfand, and Twitch shows me eligible to claim the Pouch of Violet Dust IF I connect my account. It IS connected. I do not know what else I can troubleshoot.