Yesterday I tried to send some BTC to GDAX from my wallet.
At first it seemed fine, my balance was reduced and I waited and waited.
Than after a while my balance was restored and it seemed like nothing ever happened.
What can be causing this ?
P.S.
I use Jaxx wallet.
It was most likely caused by too low of a fee that made the transaction not get confirmed on the network. If the fee was low enough, the behavior of your transaction fits that of a transaction with a fee so low that it got dropped within the day from your own mempool. I am not familiar with how Jaxx manages transactions, as I have never used it myself, but it might not have been able to calculate the fee automatically. Do you have the transaction hash? This would be a sure way to confirm these suspicions. If you look up your transaction on block explorers such as Blockchain.info and do not get a result, the only possibilities are that it got dropped as I mentioned before or that for some reason the transaction was never broadcast in the first place.
If my suggestion is correct, then yes, feel free to try again with a higher fee and it should succeed next time.