There could be a number of reasons:
1) The bitcoin blockchain could be congested;
2) You may not have sent enough BTC to expedite the transaction (you can pay a higher mining fee to relay your transaction faster);
3) Or there could be an issue with one of our third-party relay systems that we use to display balances and push transactions.
Please try to give it some more time (it could take up to a few hours if the blockchain is congested) before contacting support.