My group does not have this problem. Sounds like someone in your group has figured out a hack. Report the problem directly to EA through you game.
Sorry I messed up I was thinking how Facebook friends pictures show who bought items. Someone in your group is flat out stealing the item by sitting on your city when they know you are going to sell. You could start a new club and demand members all become Facebook friends so you can see who is buying what. Best of luck.
Since this is about updates and that it is good now we can see when some one has sent a message in the mayor's chat. I have been reading in the fan group about a cap on offers to max 20 and no more, for example, one can only get max 20 burgers and not anything up to the number one has in the game no more. Say if have 100 of the same item, feeds or electronic complements, that get an assignment on to do 60 and need to get rid of them to clear storage and only get an offer at max 20 need to get rid of at least 50 if the next task is another. Tfactory production, That how I used to clear storage when my depot was full sometimes. Now that option to clear more than 20 is gone. So if I get one factory production after the other, I have to beg friends to buy my items to clear storage. if I have to clear 50 or more for the next factory production. EA is making this game more difficult as it is on trying to clear storage from factory production assignments. Now and again I get offers when I did a task of say 55 to 60 factory items I get an offer of say 35 sugar and spices and I say yes as that clears my storage. Now am lucky if I get offers now to only clear 9 of the factory items, I still say yes but more to get rid of.