I use Coinbase, and have never had any problems selling and getting the USD back to my bank. Have you uploaded the documents to verify your identity? If not, that may be the problem.
Once you find someplace you want to send to, don't use Coinbase, login to GDAX with your Coinbase account, and deposit the currency via a transfer from Coinbase, which is free, into GDAX. Then withdrawal your currency from GDAX into whatever wallet you want, this is also free. If you do it within Coinbase, there are high fees.