Just an update since there does not seem to be a 2014 thread on the subject: But, I just tried to buy a few BTC using Coinbase near the bottom just after Bitstamp announced their fix. So, of course Coinbase canceled the transaction as "high risk" after the price went back up. So, take it for what it is, more of the same...
How many btc are you buying? Is there anything that could be snagging from your banks end? I have used coinbase for awhile and have bought at the bottom on several occasions and never had this issue