Apple Watch 3 Over-Counts Flights Climbed

I purchased a new Apple Watch 3 (non-cellular) in May this year. It seemed to be working great and I loved that it tracked my steps, flights climbed, etc. I updated to the latest Apple Watch software (watchOS 4.3.2) when it came out and, as of July 16, the Activity app began massively over-counting the steps I climb on a daily basis. It generally says I've climbed between 100-200 flights per day but the reality is more like 10 - 20! As a result, I also suddenly began hitting my exercise goal every day, whereas previously, that was difficult for me to do (and I did not change the goal).

I followed the instructions to recalibrate the watch but it's made no difference at all. General movement and steps seem to be counting accurately and walking workouts record accurate number of steps, miles, time walked, heart rate, etc. Nothing else was changed and all other watch functions seem to be normal. The flights climbed are visible through the Activity app on my watch as well as in the Health app on my phone (which is how I can pinpoint the date when things changed). The watch is paired with an iPhone 8 Plus which is also running the latest software (11.4.1).

Thank you.