I think that the plants are probably going dormant as a response to heat stress. These plants typically grow in cool conditions of the Australian winter/spring. Humidity is not an issue with them, but photoperiod and temperature are. If you want long term success in terraria, take care to keep the temps down, and vary your photoperiod to match the seasonal norm, and give them as much light as possible: they are light hungry plants. If the plants are continuing to form traps, they are not dormant, but if no traps are forming in the plants center, reduce the watering a bit, and cross your fingers. With the onset of cooler fall weather, they should start growing again.