I know I'll never get an answer from Coinbase, so I'll ask you guys.
I transfered 1 BTC to GDAX, thinking I might want to sell it at $10,000 (OMG, $10,000!!). Changed my mind, and I'm going to put it over in coinbase for a day or two. So anyway, it shows I have exactly 1, but when I go to 'free' transfer to Coinbase, it shows .993xxx BTC max, which is $64 less than a full bitcoin. Can't figure out why, coinbase transfers should be free. Guesses?
1. It could be $10k limits that you have talked about.
2. It could be transactions fees charged on the transaction, perhaps a bug on coinbase's side.
Best thing to do is probably just send the max amount now and contact support to see what's going on. At least you are still able to send the vast majority of your funds and the amount that is unable to be sent is under 0.01 BTC.
Personally, i have no idea.