ok so i have quite a few adults that does not look like there brumating. But they eat less and go to sleep about 3 hours before lights are out. Are doing a light brumation??
Have you adjusted their light cycle? Generally, cutting back on their lighting starts their brumation.
However, not every dragon brumates. None of mine even attempt it, not matter if the lights are on for 5 hours or 14 hours.