Wrong trade sales

Hello everyone! I want to report a bug. I've noticed that discounts work wrong. More precisely it is displayed right, but discounts don't work. For an instance, a villager offers me 1 emerald for 6 wheats, but it earlier cost 13 wheats.

1) When I give him 6 and he gives me 1 emerald, he makes a strange noise like he didn't like the trade and nothing happens. So the wheats are given me back and there isn't any emerald.

2) When I give him 13 or more wheats (like it would be without any discount) he sales 1 emerald and it shows that I have 7 wheats after the trade, but if I drop wheats or do something like that, it shows that I have nothing of wheats and I have 1 emerald. It looks like if I would buy it without the discount.

In conclusion, I want to say that any discount in Minecraft 1.14 doesn't work it is only an illusion. Displaying discounts works, but the system of discounts doesn't work.