I've set a countdown timer and then asked it "how much time is left on the timer?" and it says "You have no timers set" then inside say 30s, the timer goes off. Has happened to me a half dozen times in the last 2 months (at different amounts of time left obviously). This was my primary use case of alexa and now I just use Siri on my phone when my phone is nearby. Siri isn't ideal as I find it hard sometimes to quickly see how much time is left on the timer. But at least it doesn't forget one is running.