Bartering with Piglins doesn't work properly

I've just tried the beta version, then I created a flat creative world. After that, I built the nether portal with obsidian and flint and steel. Then I met piglins. I'm trying to barter with one of them with golden ingots but something wrong happens. I got obsidian and flint and steel only randomly after bartered. No other items I've got from them when bartering. I think this is a bug.