Trade Office view of lots offered - can only by 1 lot in an offer

I was doing some small trades with a new friend through the TO (since we couldn't do it direct yet) and I noticed that if he listed 4 lots of something and I bought one, I could no longer see the other lots. If he posted a new trade offer I could see that but again buy only 1 lot. I tried waiting, refreshing the TO, refreshing the game and re-logging. I still could not see the remaining offers.

It seems once you buy one lot out of an offer that's all you can get from that offer. I could understand that there might be a rule in place to prevent players from hoarding up all of a certain items to control what is listed (which I wouldn't have a problem with) but I'd like to know for sure if this is by design.

It seems to be by design, but afaik there's really no official info here about the lot option.
[Patch Note] New Trade System

i'd rather the same person could see all 4 lots, i don't really see how it could help hoarders. Also why can u do this with some items and not with others? its frustrating if u want to try and sell certain items, especially if we are expected to pay for more slots. Perhaps if these slots were more expensive but permanent it might be better?

You do realise the current lot system means can easily put up 2 ls in one trade and guarantee 2 different people buy them? That's a convenience I'd rather not lose.
I think it's a good thing really there's some spread on the trades so other ppl ahve a chance to see trades that might be popular. IN this case a buyer over seller benefit.

That some of the stuff can't be lot:ed is an unconnected but annoying problem I'm not sure BB has realised. After all we had to tell them to fix the trade sizes on different stuff too to somethign more reasonable.