This scale is garbage. I previously had the Fitbit Aria which is much better, but as is the case with all these ecosystems, they are intentionally incompatible with one another - after three Fitbit watches in a row broke on me, I switched to a Garmin watch and found I couldn't sync my Fitbit scale to Garmin Connect. It's useful having weight measurement linked to Garmin Connect so I can see all my stats in one place and the watch then incorporates my weight into it's fitness assessments etc. so I forked out for the Garmin scale just to keep everything in the same ecosystem.
The scale is easy enough to set up, but about 3 out of every 4 times I step on it, it fails to sync to the Internet and I see the dreaded "X" in the top right corner. Sometimes it will work 5 minutes later, sometimes it won't work for a week. Resetting to factory defaults, rebooting my router etc. makes no difference, and if you Google it you'll find dozens of people complaining about the same problem. It's probably a compatibility issue with some kinds of router so perhaps most people won't have this problem, but if you do have it, there's nothing you can do about it. Garmin don't seem to be updating the firmware for it any more and their support team tried troubleshooting it with me for an hour and a half with no success. I could send it back but that would leave me with an even worse problem of having no scale at all that syncs to Garmin Connect, so I'm keeping it begrudgingly.
The good news is that even if it doesn't sync for days in a row, when it finally does sync, it will send all the weight measurements for the previous days (as long as you don't reset to factory defaults in the meantime), so you don't actually lose any data, it just means that often your weight chart on Garmin Connect is a few days out of date.
It also started reporting my body fat % incorrectly for about 3 months. One day it dropped the percentage by literally 7% in one day, as though I had become an Olympic athlete overnight and it stayed around that number until I took the battery out and re-seated it months later.
Finally, it reports on things like bone mass but those figures are absolute bunk as far as I can see - based on a simple calculation in the same vein as BMI. My bone mass chart for example has a nearly identical shape to my weight chart - in other words it thinks my bones are getting more or less dense in perfect synchronicity with my losing weight, which is nonsense. Oh, and this is about the most expensive smart scale on the market.