I've been puzzling over this issue for the last few days and weeks.
The bitUSD:BTS volume shows 0 on coinmarketcap. I wrote to them about it and referred them to cryptofresh to get the correct numbers, but then I check and the USD:BTS volume shows 0 on cryptofresh too!!
This is clearly wrong because I've been generating volume on that pair. lol. Also I can see in my BTS wallet that the volume is 1.47M BTS or 6.7K USD. Adding this volume would bump the bitshares DEX up in the exchange volume rankings on coinmarketcap. One day I expect it'll be right at the top.
Please fix this as soon as possible! Anything I can do to help let me know.