Apple Watch not registering flights of steps

My Apple Watch 6 is very inconsistent when counting flights of stairs. Sometimes when I walk a specific route it says 5 flights and some days walking the same route it says 0 flights. I’ve reset privacy/motion & fitness/fitness tracking and Health. The operating systems on my watch and my iPhone are up to date. Today I walked up 175 steps, at one time, and the watch/phone didn’t register any flights climbed.