lose data
I did a factory reset of the computer twice this year, and every time I was syncing my data in Mozilla Firefox, but unfortunately when I log into my account I find all my data has been lost, including passwords and accounts. What's the reason? Can I trust this program after these two attempts ??
Opaite Mbohovái (2)
its possible that you were not syncing, though you thought you were doing so.
its also possible that maybe you sync'd to a different FF account.
but who knows.
try a test:
create a new profile. and once invoke, dont do nothing except a sync. sometimes it can take up to 5 minutes to download. but there should be a spinning wheel to show that syncing is currently be done.
go to url and find / use create button:
about:profiles
Note that Sync isn't designed to be used as a backup, but is merely meant to sync data between connected devices.