Here's the situation.
From time to time, when I try to sell some quantity of an item I get such popup:
It happens when just before the moment i click sell, someone else just sold his/her items for that price.
It's obvious I can't sell the items if there is no buyer but this is strange behavior which shouldn't have place as I intentionally don't LIST ITEMS but SELL for buy price. I really expected the rest of items (unsold) stayed in my inventory. In my opinion current system is quite unfair. I want to sell in NOW, I'm not going to wait for cash and I don't want to risk never selling it because of sometimes very quickly lowering price on TP. I already had situations where these items had no chance to being sold since price dropped very quickly.
I'd recommend changing the behaviour of selling system to not listing the rest (unsold items for wanted price) but leaving it in inventory.