Apple Watch Timer

Why does my timer not give me any notice (no haptic feedback/vibration) that it has counted down to 0:00 anymore? I have not changed any settings or done any updates to make this stop happening. The only fix I have so far is to completely erase my watch and set it up as a new one. This was what the Apple Store employee told me to do, but it is quite annoying to have to do for a third time. How can I avoid setting up as a new watch to regain the completed countdown notification (haptic feedback/vibration)?