Sync is not to be used as a backup. If you didn't backup the logins or data any sync will clear the sync and there would be nothing to sync from when you login.

Sorry to hear about this problem. I'm not sure why Sync didn't bring over your data.

You can check what data is in the Sync cloud for your Mozilla Account using the About Sync add-on:

https://addons.mozilla.org/firefox/addon/about-sync/

After you install the add-on, you can type or paste about:sync in the address bar and press Enter to load it. The page shows each category of data currently found in the Sync cloud.

Anything on the server in the crypto category?