From your case, if you completely set up Armory online, that may be your wallet is empty???so shows 0 balance
You can get your private keys from offline wallet, but you need to check which address have btc from online watch wallet. Then you can also export the key to import other supported wallet to get the btc, that is not recommended!!!
I am currently 494706 blocks on my end as of now. I'm not sure what you mean by start syn.
Bitcoin core and armory are both synced from what I can tell. Bitcoin core nor armory show any BTC.
Someone mentioned something about private keys, I can see a bunch of those if that means anything.
Armory is 0.96.399
Bitcoin core is v0.15.1