Within the last two months, I have opened up 6 hyper crates, and a bunch of extra other cartel packs as well. And I have not gotten a single cartel certificate for trading in to the vendor for different items (Twi'lek dancer for instance). I remember a few months ago those used to actually drop, and a lot of other people I know in game have had the same problem with none of the cartel certificates dropping.
Is this a bug, or do I have dumb dumb luck?