As you all know by now, the Galaxy Watch 4 (and the Watch 3) did not correctly count floors. I know this personally because I owned both. I think I figured out why:
Floor counting doesn't work if the screen is off. If the screen is on, it works (mostly).
The issue I had was that I do not have the screen "Always On" because I want to save battery life. I switched the watch to always on display and, sure enough, floor counter started working.
There were a number of proposed solutions that involved resetting the watch and clearing cache. This is a waste of time.
I would hope the firmware engineers at Samsung, now aware the cause, and solution, can easily rectify the floor counting problem that has plagued this watch forever. Please issue this simple fix in your next software update.