With the recent IOTA protocol upgrade, a new wallet version was released - please don't forget to install it and to send your old seed balance to a new one!
Further informations here:
https://blog.iota.org/new-gui-transition-phase-explained-b536ed80f412
I understand nothing is lost if you do not upgrade right away. But it never hurts to timely upgrade.
Your IOTA SEED is valid but the recent protocol upgrade was one of a row which will come up in near future. It is suggested to transfer your funds to a new ITOA seed. In order to do this, the new wallet will help you with that.
I just updated my wallet, and have a 0 balance. No word back from the slack chat yet. >.<
Edit: I went back to the old wallet and my balance is still there.
Hey, the zero balance is correct. Have you created a new seed, reattached it ? After that you need to attach one or two new addresses in order to see the correct balance.
Cheers :-)