For the record.. As of now transferring out ETH from GDAX/COINBASE is not possible. Currently etherscan shows : A total of 1467 Pending txns found.. This is a very low number. It seems that GDAX/COINBASE is arbitrarily imposing a hold of assets not expressed in the terms and conditions of the agreement. BTW I don't have a margin account.
If all is fine and dandy why are you holding people's funds?