Where is it located in the house? Try putting it in a south facing window..
A lot of plants are biologically prepared to store or expend energy based on what time of year they think it is-
that can be based on light duration, temperatures, day/night temp fluctuations or moisture levels.
Be patient. Are you dying to display it in dirt vs water? probably not. If you are in the nothern hemishphere, days are getting shorter- that may be a signal for this plant to slow down and store energy, waiting to explode when conditions are right
