I just bought an index S2 yesterday and set it up. I added my wife and myself as users with me as primary. It took a few tries yesterday but eventually it recognized my wife.
Today when I went to weigh myself it did not recognize me, and when I attempted to scroll through the users all I got was question marks. It didn't display my wife's name or mine.
It is showing as connected to wifi, I even moved in the same room as my router. The garmin website is showing no syncs since yesterday when my wife weighed herself.
I and disappointed so far with this setup, I'm switching from a Fitbit Aria and at least if it did not recognize somebody I could go on the app and assign the weigh in to them.
Anyone have any ideas? This is more work than it should be for a $150 scale and I am likely to return it.