Hi, Drained, cleaned, and refilled our tub. Left on Saturday afternoon and tonight, (Sunday) our tub was empty. There doesnt appear to be water coming from the drainage hole. We currently are refilling the tub to assess how quickly it is draining and maybe see where the water is leaking from. The weather was -4 but the tub was reading 60 degrees so we don't think anything could have frozen within the hour and a half it took to clean and fill. What could have happened? What should be our next step?