Did you experience a bout of cold weather recently? Hawaiian Ti's can't tolerate temperatures below 50 F.
What kind of water do you use? Poor water quality could be suspect. Try switching your water to non-fluoridated or distilled water, as fluoride is mildly toxic to hawaiian ti plants.
I am also wondering about letting the soil dry out between waterings. In the midst of my research I was getting conflicting information. Many resources I found said to water enough to keep the surface soil evenly moist (not soggy). It's something to consider anyways. You may also want to consider fertilizing it if you haven't already.
For more information on growing hawaiian ti plants, please visit the following link:
https://www.gardeningknowhow.com/houseplants/ti-plant/growing-hawaiian-ti-plant-indoors.htm