So I tried this new feature and it worked just once. The next day, when my game got sold, I had to redo the trade all over again.

Also, I think I have found the problem with this one - do you have a specific time frame on how long this "permanent" setting will be? The first time I made use of this, it worked because I immediately replaced the "sold out" trade (I guess within an hour?) with another set. The second and third trades, however, it took me around 8 hours or so (it was 1AM and I woke up to check my Dispenser at 9AM).