I just received the following reply from Gigabyte tech support:
Dear Customer, The TH devices are currently not yet available, it is still under validation. Please check back towards the end of first quarter of 2015 for updates. Thank you.
Gosh, I wish the marketing material for this mobo made this clear. It was very misleading to say a list of approved TH cards are on the Gigabyte website. I bought the X99 mobo now thinking I could easily add a TH card, not expecting to wait another 6 months. Foolish me. Shame on you, Gigabyte.