Oh no! I’m so sorry that happened—how frustrating! Chocolate can be a little temperamental, especially when adding ingredients after melting. If the vanilla extract was water-based, that could have caused the chocolate to seize up. For next time, a few tips that can help: try using an oil-based or alcohol-based vanilla, or stir it in just before the chips are fully melted to help avoid that reaction. I really appreciate you sharing your experience—it’s helpful for other readers too!